You have done a fantastic job on the 1st room. Well done and I bet it felt amazing standing back and seeing it done .
Regarding the second room, your son that is coming over tomorrow, would he be willing/able to help you build the bed ? That's a fairly big job.
There are some great suggestions here, however what is, if any, your budget on buying for storage etc ? I know those units etc are expensive.
I have 5 children, they're mostly grown now but they were all little once and my house felt like a toy shop and tip at times. I wasn't able to afford units from different stores , I use to have tons of the coloured boxes from Argos, I'm in Ireland and Argos are gone from here so I'm not sure if they still sell them. They were reasonably priced, held tons, they could be stacked if not overfilled, were fantastic for bits, figures, Lego, smaller toys, I always managed to fit in as much as possible, actually, IKEA do similar boxes, I know you can't get there but if you were ever to get the chance. You don't have to put these plastic boxes on units, they can sit on the floor until you are able to buy the units. I also used the big massive clear plastic storage boxes, I always found these brilliant, affordable and so, so handy to just throw things into. I also used , I can't remember the name of them but they were a tall plastic trolley with 3 big pull out drawers, I think they were advertised at the time for kitchens for holding vegetables, but I put toys, books, crafts into them, they also held small toys and the trolleys were in wheels so you could change them around the rooms easily, everyone had their own colour trolleys.
I remember trying to make the rooms feel nice, I think once the floor is clear, tidy and beds made the room looks much better. I remember cutting out characters from a colouring book one time and I stenciled them onto the walls, just drew around them and I had small paints from a child's craft set and used them to colour in the stencils I just drew on. It was temporary until I was able to afford proper units, proper paint etc
Oh and I used laundry baskets too for storage of toys , folded bed clothes, jumpers, shoes, some nice sturdy ones, some with lids. I got my kids at the time to colour their names onto A4 paper and I put that in an A4 plastic sleeve and I sellotaped it to their boxes, baskets etc
You're doing great, your kids will be delighted, when you have extra storage it's easier to keep tidy. Still to this day I have a big plastic container in most rooms and it's a quick tidy up just throwing things in, but try keep to samey things you're throwing in as it's a pain sorting and looking for stuff if it's all mixed up