Having sex while pregnant !!

What are some good positions that we can try to be more comfortable. I’m so sad kind of tonight hubby was so tired he could not finish like he usually do. He say it’s not me or nothing but idk . Tummy is getting big and is in the way we usually do riding and doggie but tonight this did not work. And I’m tired also . Ugh oh well I guess we will try again later . Give me advice and your experiences everyone is welcome!