Hallo dlmds, Im no expert on pillows. My I advice be to buy a bigger pillow, take your cover with you to make sure it fits, or do it the hard way, make the cover smaller.

Did you measure the pillow form??? I think I would take my cover to the store and TRY different forms...I know that if you make a round pillow cover you get a fuller pillow if you squish a square form in it...learned that from my MOM!!!

Can you post a picture? It is hard to say, it might just be the pillow form. Have you tired with a bigger pillow?

Did you try adding more stuffing?

Also you could try adding a button in the centre of the cushion, on on each side, stitch right through each one with strong thread and pull tight. I have especially long tapestry type needles I use for doing this sort of sewing, just makes it easier and I have a pair of locking forceps to grab hold of the needle if I have trouble pulling it through.

If you follow the link below, you will see I have added a tying ribbon to one side of the pillow, the other side has a red, four hole button, which keeps the thread secure and prevents damage to the pillow.
hope this helps. hugs n roses, M

I think you made your cover too small, you must remember to always add ease to everything you make, the too small cover can also push the pillow in and not allow it to plump up. Just one centimeter can make a huge difference. Hope it helps, and I read your question right. *for u