yikes, that is a really small picture, not sure if you're going to be able to see it very well. I was also only able to add one pic, couldn't add the master plan, sorry. Again, new at this :(

If you don't want to borrow from anywhere else, then your original idea of putting the toilet at the end of the vanity is your only option. You will have room for some storage on the end of the tub, but the first thing to do is choose the exact tub you want. Also, if you widen the door, you'll have the keep the vanity and/or tub narrow. I think the narrowest vanity is about 18". So 18+36door+5"molding leaves about 31" for a tub. I understand wanting to widen the door for a wheelchair, but what are your plans to make the rest of the room ADA compliant. One thing you can do eliminate cabinetry under the sink having just a countertop. Just something to think about.

I have thought more about this. Like Beth said, you could really get a lot more in that bathroom with only one door. I think I drew what she suggested. As far as the door between the two areas, I think it could go either way, but if possible, I think a pocket door that slid into the area by the tub would be better. This would keep the door from being in the way and be almost entirely hidden if not in use. I had one additional thought as well. Assuming later down the line there are additional children or the house is sold to someone with more than one child and bedrooms 3 or 4 are used as bedrooms. Is it going to be fair that the bathroom opens into bedroom 2? Seems like that might cause some disagreements. On that same thought process, the one thing that might bother me would be seeing into the bathroom from downstairs. Although this puts you right back in the same position having bedroom 2 walk around the corner to get to the bathroom, the view from below will be nicer and access will be more even between all 3 bedrooms. If doing something like this, I would extend the vanity the entire length of the room for plenty of storage underneath. (This is the placement of the bedroom door from your first drawing.)

You could add interior shutters to the window facing the street, even doing just the bottom half would block most of the view. Or you could replace the window with one the same width but not same length and place it five feet off the floor for privacy. The privacy is easily addressed. However, the driving issue will be cost and feasibility of adding a toilet waste stack. I just added a bath addition to the side of the house that had zero existing plumbing. I lost 6x6 " in the sunroom below for the waste stack to be added, is there room by your front door to add a chase for waste? I also lost almost an additional $10k to run the new plumbing inside and outside to my existing sewer line. Your plan will most likely in tale outside excavation work too. My drive and walk way needed to be replaced at another $10k because my sewer line to the road was under my existing walk and driveway. My driveway was at the end of its life anyway so this cost was something I needed to spend regardless of the addition but it would have changed my plans if it was a decent drive to begin with. I am not saying you will have these identical costs. Yours could be much less to address adding plumbing where none existed before but it could also be even more...get a few quotes on both options and make sure it is permissible before deciding.