Is it the size of the boat or motion of the ocean?

I recently started seeing someone and he has a smaller size penis. I’ve never came while having sex with him is it because his size or is there something wrong with me? I really like him and I don’t want to end it with him over sex and seem like a shallow person. We do oral, and that feels good, but I never come during oral sex either. What should I do? Is there any tips to help with stimulation for us?