Question for any high elo or skilled player of LoL

If behind as an ap carry mid, like: oriana, ahri, syndra. How do i go about team fights. I have little to no items i don't do much damage, i am super squishy and my team is not doing to well. The other team is not so far ahead where its unwinnable. I know you're supposed to take up more of a support style; but in that situation where there is no one who is fed that can deal out the damage what should i do?

I'm at a loss because i don't know what to do if we don't group and try to farm up they will just force all mid. Also i'm to far behind to do a catch i will just get out dueled and my team won't help with the catch style they just want to group and defend.

Thank you for reading hope to find a solution.