What Oats asked. Are you very experienced or not?

I'm going to guess not and if that's right, your problem is likely due to nerves and masturbation. Your hand is way more stimulating - tighter, faster, etc - than a vagina so it's possible you're just used to that and are going to have to cut out wanking until you get used to cumming during sex. If you're nervous that'll do it too.

One problem could be improperly fitting condoms. If you wear ones too tight at the base they kind of act like a cockring and make it take forever for you to cum, or you go soft. I had this problem for a while until I put 2 and 2 together and tried different condoms. You might not need large size condoms but different brands fit a little differently, try a sampler and find a kind that works for you if that's what's doing it.

Also it's not too weird to not cum from a blowjob. I've only been able to like twice.