Serious question, will I know when I orgasm? (TMI info included)

So I know I'll sound like a 13 year old (Im 21 and married), but will I know if I orgasm? My husband and I have tried so hard to get me to orgasm, but we havent had success. We have been married a year now. Together a year and a half. We have an emotional, mental and physical connection during sex. We have tried breast play during sex, clitoral stimulation during sex, different positions, just clitoral stimulation without sex, using a vibrator, oral sex and plenty of other things but nothing. My poor husband feels like a failure. And hes not small or anything (if that actually matters). Only thing is he tends to not last too long. Ive been with other guys before my husband (never in a serious relationship) but none of them got me there either and some of them tried.

Ive masturbated and tried to get myself there. I had a dildo/vibrator I used, Ive had years of practice. When I try I tend to have a feeling building up, but it feels like I just hit a flat point of feeling. Like thats as much as it gets. Imagine like going up a mountain. You go up and reach a ledge and it feels good to get that high, but you know theres something else. Thats how I feel. I think I might have orgasmed once years ago, but I cant be sure. I was like 15 at the time.

I know mentally about how to orgasm. Most women need clitoral stilumation during sex, women take longer than men in general, ect. But that doesnt seem to help much. Lastly my clit is either really sensitive or not enough. I think its overly sensitive. I wear panties when I masturbate. And when my husband rubs my clit a little hard or fast it hurts. Its too much. It doesnt feel good so I dont want to continue. But if he rubs slow and gentle I feel nothing. Any advice or experiences in appriciated. Even my sisters looked at me weird and just said stuff about the clit. Like ya I know. Hasnt helped.

*Posted anonymously out of pure embarressment*