Very little semen leakage after sex? Help please

So I have noticed the last several times having sex with my husband that when I get up to use the restroom, there’s zero mess to clean up afterwards. I’ve been using a cup after sex during my fertile window and even then the only thing I notice in it is PreSeed. He’s in his 40s and tells me that as he gets older there’s just not as much. But I can’t help but feel like it’s something else.

I have asked my husband if he finishes and he swears he does, I just never see any evidence of it. I’m starting to wonder if this is why we haven’t been successful yet and if he’s faking it or something. I know I probably sound irrational. Has anyone experienced this before? Or have you experienced it but still ended up pregnant?