I cannot go on top for the life of me!

Ive had other girls workshop it for me even. I have guys during double bookings to get the other girl on top while i do other stuff. Sometimes me going on top even makes them soft! Im only a small person also. I think i just cant get the mechanics of it right and also it barely feels anything for me in that position so its hard to get into it.

What can I do to help with this? Is it okay to just be a bottom and tell them this?