I’ll start off by saying that I’m 20, so not much older than you, but my SO and I will be celebrating our 4th anniversary in a couple months so we have been together significantly longer than you and your boyfriend.
There really is nothing any of us can tell you to make you stop being jealous and to trust that the situation won’t go into inappropriate territories with his friends. I know you say you trust him and don’t trust them, but this statement doesn’t show that. If you truly trusted him 100%, you wouldn’t have this worry because you would know that NOTHING would happen, no matter how much they wanted it to, because he wouldn’t let it. Trust is one of the most important things in a relationship, along with communication, and both are even more important when you’re in a long distance relationship because you need to rely on them more and on other things less (ex. intimacy).
You have also stated that you get angry at him if he doesn’t tell you what he did when he hung out with his friends when you talk later in the day. I know that you don’t mean it this way, but this seems a bit controlling. He should be allowed to have relationships with people nearby and not have to give you a play-by-play of his day every time he hangs out with them. Just as it would seem controlling or nosy if he made you tell him everything you did that day, this doesn’t seem healthy. Again, it comes to trust but also to privacy.
The other thing I have noted is that you say you Skype, call, and/or text “all day” and get mad at him when he won’t talk to you when he’s at his friends. This is mindboggling to me. You BOTH need to have your own friends, hobbies, and interests that are separate from the other person. I know it isn’t fun when you don’t get to talk all the time (SO is about to finish a placement and go into a job as a paramedic, which means shiftwork, so some days we have limited communication). However, this is OKAY and perfectly healthy. It is a sad part of a long distance relationship, but the more quickly you adjust to spending stretches of time not communicating with him the easier it will be. (This also comes in handy if something comes up, like working in an area without cell service or one partner going on a trip where they won’t be available to communicate much.) What I suggest is finding something to do that you really enjoy to pass the time in addition to finding a job and/or going to school to keep you busy. I promise, the busier you are the easier it is to spend long stretches of time apart.
I am not saying that you and your boyfriend don’t love each other, but these are just some things I’ve noticed. I would also recommend slowing down… there is no need to plan on moving in just yet! Yes, I know it isn’t what you want to hear, but it is the truth. Even though you talk to him online all the time, that isn’t the same as actually being with him. Many times, you feel more or less chemistry with a person you’re talking to online than you do in real life. You can not truly know whether a person is a good match for you until you have spent a significant period of time together, in person, doing things. Long distance can sometimes be stressful, but it is a different kind of stress than, say, getting stuck in traffic or financial issues and the way a person deals with the two can be quite different.
I truly do wish you and your boyfriend the best. However, I think you definitely need to sort through a few things before you get ready to move in together, and certainly before you get engaged. I know that waiting isn’t fun (SO & I have been together since the spring of 2008 and I’m not expecting a proposal before our 5th anniversary, and we may be together 6 or 7 *years* before getting married), but for youngin’s like us, it is often the best course of action.