I feel for you! I had exactly the same thing with one of mine this year! (maiden) She went 367 days. She didn't bag until 12 hours before she dropped baby, back end really dropped and she got very sensitive about being touched anywhere. By which stage I was out of my mind with when it was going to happen and throughly sick of all the txt messages asking if she'd had it yet
Sounds like your girl is def close with the dropping etc.
One thing I would watch for is the hoof length, my filly came out perfectly formed, straight legs but had hooves the length of a month old baby. (Which figures as she was a month late....) Farrier did them within first week and was quite surprised when I told him how old she was.
She also was the most active foal I've ever had. She never had a sleep until she was about seven hours old and hooned around the foaling paddock. Figure she was making up for all the extra time baking. She's also growing a lot faster.
Friend of mine had same issue with baby going overdue, as well as hooves and growth rate.
Best of luck and look forward to that baby