I think your'e not insecure. For now just do some observations. It is not good to judge him when you don't have enough proof. And if your suspicions is enough to be revealed, try to talk to him and tell him what he want to do with your relationship.

And about making love, try it again if you two have the chance. Then if he always do (withdrawing, lose her erection when he is inside of you), Talk to him again also and ask him why. Tackle about topics like didn't he want to have a child?