I am 16 years old I have been with 3 girls and it has always been a problem for me to orgasm. I used to think it was because my ex-girlfriend had been with quite a few people and now I'm with a girl that has only been with one other guy and it still takes along time for me. Is there something wrong with me?
Let's get one thing straight right off: there's almost certainly nothing wrong with you.
But before we go any further let's clear up one other important thing: the number of partners a woman or girl has had has nothing at all to do with how easily you can have an orgasm with her! I'm not going to throw out the old cliché about how a baby's head barely makes a difference so how could anybody's penis because that doesn't seem to work for a lot of people. Instead I'm going to ask do you think playing a lot of basketball makes it harder for your hands to hold a basketball, or if catching a lot of footballs "loosens" your hands so you can't catch them as well any more, or maybe if drinking a lot of soda out of soda cans "stretches" your fingers so you can't hold a roll of quarters or a pencil. And you're probably looking at me and saying what a chump, right, because hands have all these muscles and everybody knows muscles expand or contract to hold whatever it is you want to hold, however often you want to hold it, right? Well, a woman's vagina is muscle too so no way it makes any more difference how many other guys she's been with than it matters to you how many times you've done something with your hands.
So if it's not a matter of how many partners your partner's been with or how often, and you think you're having trouble, well there are other possibilities to look at.
One possibility that you can't rule out is that you're getting better at what you're doing, which means your partners are enjoying themselves more, which means they're making more lubrication, which can mean you're not getting as much of the kind of friction a lot of men need to have orgasms. Not the worst thing when you think about it, but maybe still frustrating. If that's going on Heather has some answers to someone else's questions in"Too wet for good friction?"
Another possibility might be that it's just taking you longer to have an orgasm during intercourse than when, say, you masturbate. The sensations are usually pretty nice for both, but especially depending on how you masturbate, they can be pretty different too. And despite all the stories that say otherwise men aren't just automatic ejaculate-anywhere machines. Along the same lines if you're using condoms for intercourse you could be getting a slight reduction in sensitivity that makes it a little harder to have an orgasm when you want to. If either of those things are true, though, the answer a lot of the time is to be patient and your nerves will strengthen the pathways between your genitals and your brain and orgasms will come easier.
There are other possibilities from just plain old different reaction times for different people (some people can take longer or less long than others and still be normal), to just not really having enough time, to having other ways that work better for you, to feeling stressed out about it (just that can slow things down for you), to some medications you might be taking, to depression, or to overuse of certain "recreational" drugs or especially alcohol.
The good news is you can find people to talk to if you're concerned about depression or substance issues, and you and your partner can talk about it and work something out if it's anything else.