Sexless relationship... I'm stuck! Help?

My fiance is dependable, caring, he loves me and would do anything for me. We are 44 and 47. I said yes to my fiancé's proposal before we had had sex. I didn't really realise that he has a small penis. And because he isn't well endowed he stayed completely away from sex and dating. Therefore he isn't very experienced, confident or skilled in the bedroom. I've never been with a man that I don't have an intimate connection with. Besides sex, he doesn't say or do anything that really turns me on. We do have a lot of care, love and support between us though. Consistency, honesty, nurturing. But I'm so in my head because now that we have a 4 month old child, I worry about how I can commit to a marriage when I can't imagine being sexually / emotionally fulfilled. I would like to stick together as a family. I don't want an open marriage. I don't want to break up and have split custody. I've tried and I cant teach him how to be better in bed. We've done therapy, seminars etc.