If you can only go upstairs when your DS is there maybe the best thing would be to gather what you need for a few projects. Before you go up list what projects you want to do next. Plan on being up there for awhile as you find the patterns and everything you'll need for each project. Maybe batting can be brought down closer when you will actually need it.
Organize the space again and take detailed pictures so if you need someone to go up you'll be better able to describe what you need and where it is stored.
If this is going to be a long term health challenge consider looking for a used stair lift to perhaps enable you to go upstairs at will.