my 2 bobs worth. as someone who works with the elderly-the en-suite for your MIL is still not right. if she ever needs walking assistance,especially with a frame, getting past that door into the en-suite will be a nightmare. swap the vanity position for the shower. ensure there is no step-down into the shower area, and ditch the shower screen for a curtain. will make access much easier. especially if she ever needs assistance showering..it will be virtually impossible, and dangerous, with your current design. thinking long term..MIL will not always be there with you, so presumably you and your hubby will at some point end up in the master bedroom? consider the long terms implications of this-no good building something that suits her now, but would need major modification to suit your needs later. I would actually do away with the WIR at this time. Plan to add it later, if you would want it for yourself, but i would just use free standing furniture for her-no doubt she probably has her own, so it would be nice to have some of her own furnishings when she moves in with you - to make it feel more like her home. it will free up some floor space, and make access to the ensuite easier, without having to turn corners. I would also do away with the extended passage into the master. Take that door back in line with the other bedroom. Currently, it adds nothing, and may well limit your furniture placement for your family room, as the walkway will need to go around it. i have issue with the 2 person shower and double vanity in the same room. s the kids get older, they /you probably wont be comfortable using the room when you are showering, so mornings will be slowed down. Have you considered a 3 way bathroom/toilet/vanity area? We had this in our house, and it was the best decision ever. The shower and bath were in one room, with a separate toilet, and then a double vanity which opened to the passage. Everyone could use everything at the same time, without encroaching on each others privacy. Not sure about your state -but here, the toilet door would have to open out-if someone collapses in the powder room, you would not be able to get in with the door opening in, as they would be blocking the door. I do empathize with your dilemmas. We have spent 7 years planning an extension and remodel, then 2 years (!!!) working on the design with an architect, going backwards and forwards, and then the last 12 months nearly, changing and fine-tuning along the way as things were being built. It is not easy, but worth it. Having said that, you are unlikely to ever get it perfect, as your needs will change, your likes/dislikes will vary, and you will see other peoples homes and go "why didn't we do that". (Now if only i could take that on board myself, LOL)

I'd suggest framing it out and using it as a window seat. A carpenter could get that done in half a day. Anchor the frame to the wall, get a custom cushion made and fill it with some cushions and you have a beautiful space to read. Bonus is the minimal cost.

I'm still concerned that the covered alfresco area is located to the NE, it will block much of your winter sunshine from entering your living areas, making your home colder in winter. Personally, I'd try to locate your alfresco o the eastern side of your living areas (& somehow moving the master further SE). However, if you are going to stick with your current alfresco location, I'd recommend you change from a hipped roof alfresco, to a gable roof alfresco. If you make it an opened gable, & have a cathedral ceiling you'll end up with quite a bit more winter sunshine entering your house. Similar to the images below.

Great advice from all the posters here. But I love the line "Don't get blinded by the size"! Yes, the price/sqm will be higher for a smaller home, as all the expensive essentials - a kitchen, bathrooms etc - will all still be there. But the overall cost will still be significantly lower. Especially if you keep the build to a single storey! As soon as you go up, costs will increase significantly. You'll have more wasted space too, like a staircase & landing. Be ruthless, & importantly, be inventive! Australians now build the largest houses in the world. We overtook the US after the GFC. Is this something to be proud of? I don't think so. Not in this world of finite resources, & climate change. Of finite land, while we continue with our urban sprawl, even endangering something as iconic as our beautiful, & vulnerable koala. Houses don't have to be bigger, they just have to be much better designed. The rest of the world can design in much smaller footprints, why can't we! A smaller home will not only cost you less to build, it will cost less money to maintain over it's life. It will cost less to heat in winter, & cool in summer. It will cost you less time to clean, & maintain. It will cost the environment less. In resources & embodied energy during the build, & in emissions to heat, cool & maintain it over it's life. Do you really need that rarely used guest room? Do you even what it, when you think hard about the financial cost to you, the cost to the environment & your children's future? Along with the time it takes to maintain this room, clean it, dust it, when it's sitting there usually unoccupied. Wouldn't you prefer a well designed multi-purpose room, that can play multiple roles? House guests, when they come to stay. While at other times, be used as a second living areas for the kids, or an office space. Same goes with storage, where many poorly designed homes fall down. We'll designed storage is critical, especially in smaller spaces, but it can be done. OP, you've chosen a nice small block, with a nice 15m wide southern frontage. This will give you a lovely, wide, northern rear aspect. Work with it! You can have beautiful, light & bright living areas, that will connect to your north facing backyard. These living areas will be heated by the northern sun in winter, shaded (by eaves) in summer. If you haven't already, start by reading this wonderful government about energy efficiency home design. https://www.yourhome.gov.au/ There's a lot to take in there. But if start with the passive design section. You've got a lovely northern aspect to work with, & this website will teach you how best to take advantage of it. There's even house plans in there somewhere (in the menu). Not sure if there's anything appropriate for your block, but I'm sure you can learn from them, & get some ideas.