Maybe TMI? Delayed ejaculation?

My husband can't cum through just intercourse. He has to use a vibrator. So, what we do is, have intercourse for a good while and then he gets off with the vibrator. Right before he cums, I either jump on top or he gets on top of me. All or most of the semen gets in me but we've been trying for a long time. He's convinced that this is why. Has anyone gotten pregnant with this issue??