Penetration problems (HELP!)

I don't know if this is in the right category, but please help me out. This has been bugging me for soo long now - most virgins would know how I would feel when they have sex for the first time. I've had (well attempted..) sex three times (with three different guys each time). My first time was when I was 15, with a guy my age who had some experience. We did about 10 minutes of foreplay, he fingered and licked me out which got me wet - so I was hoping that wouldn't be the problem. When he tried to put his penis in, i was in lots of pain (I was expecting this, as it was my first time). As I am a horse rider and I did quite a lot of cycling, i didn't think my hymen would be the problem, as it had already broken. He then tried to push it in deeper, and the pain got a lot worse. He tried going in and out slowly but I didn't feel any better, it wouldn't go any deeper than half way. I was in so much pain we stopped, and left it at that (This was in December). I then didn't have sex for the second time till the beginning of June. This was a guy I used to go to school with three years ago, but never spoke to, he was 18, and basically a stranger. However he was really caring and gentle. He fingered me to start with and that felt fine, although a little painful when he put more than three fingers in. Then he went to put his penis in, and the same thing happened. He put it in as much as he could and i felt the same pain - he knew i was hurting but he said it was normal, and pushed it in deeper. I literally could not take the pain and screamed at him to take it out - it was absolutely unbearable! He then fingered me again for about 10 minutes and that didn't loosen me up at all, we tried again and again, the pain was excruciating. Again, we gave up. Then I had sex for the third time last night, with another 18 year old. We did a bit of foreplay but the same thing happened! It's now summer and I dying to finally be able to have sex like a normal person!! What can I do?! Please help.. !