Uncomfortable Sex During Third Trimester

So I'm currently 29 weeks and 3 days and I've noticed the last couple of times my husband and I have had sex that it is really uncomfortable for me now. To the point where we have to stop. It's like a burning sensation.

I know I shouldn't feel bad and my husband has been so supportive about it but I can't help but feel awful that I can't go as long and he therefore can't "finish".

Any tips/positions we can try to make it less uncomfortable?

Tried cowgirl, sideways and doggy.