It's NOT your fault - or anyone's fault.
Watch out - some frank language coming....
Don't put him or his needs first - or you or yours. Sex is a double act.
No one is good or bad at sex - couples are either good or bad at it together.
But Good sex does require honesty.
You need to discover what floats his boat - and this might not be easy.
He may not even know himself. (yet)
Here's a pretty personal story...
I was horrified when I discovered that a blow job DESTROYED my erection !
I was in my early 20s and considered myself a normal, healthy, red blooded male. I was in the middle of a fling with a flighty young thing who went down and went to town and heh presto - goodbye hard on. She was surprised to say the least and so was I. Things went on then and there and we ended up having good sex (with no more BJs) but I discovered that that a BJ just didn''t do it for me. It wasn't her - it happened again and again with a string of different women. It became fixed in my head as a truism.
Time passes...
I went on through my twenties with a few girlfriends and a few one night stands always saying "heh - don't bother - it doesn't do it for me" knowing that a BJ would kill off my hard on. And then....
I met a girl who said "what utter nonsence... I LOVE a hard cock in my mouth and I will simply find a way to make you love it too".
It took a few days (only) and I'm not going to tell you exactly what went on but she found a way (mostly with lipstick and polaroids) to make me extremely horny about having a BJ.
The same is almost certainly true with you, your husband, and penatrvie sex. It's all a question of which buttons to press. Does being "naughty" make him horny? Is it 'control' that turns him on ? Does he need to take you roughly from behind or is it all about you moaning and screaming ? Maybe he needs you to say "Yes yes" or "no no no". Most male fantasies are common knowledge - try playing them out. But if you have a decent relationship then talk is the first step - just ask him what his naughtiest fantasy is - and (if legal) try it. Could be handcuffs - could be BEING handcuffed.
You might find that he simply LOVES to fuck you with a far out and fabulous vibrator (good for you, good for him). It might be sex in the window so the neighbours might see - it might be dressing up, sex with your clothes on, date night and a cheap hotel - whatever it is, go with it - you live once.
Most men will NEVER confess their real fantasies to their wives and most will never go to prostitutes to play them out - so they end up with half a hard on. Frustrated with "normal" sex and knowing that their wives are less than satisifed or excited. It's the worst case scenario and it's going on behind millions of suburban front doors all over the contry. Women are equally guilty - they keep their "real" sexual desires a secret from their men and spend tens of years neither satisfied or excited.
I reckon the doctor is NOT the answer - I reckon the answer starts with frank and honest (probably fairly drunk) conversation and maybe some experimental moments which might go wrong (be ready to laugh and cuddle) and might go great (be ready to be a dominatrix / nun / cheerleader / covered in jelly). Play games, have fun, discover a whole new chapter in your sexual life together.
And try not to get arrested : )