First of all, I'm sorry you are feeling so down. You have been doing the LDR for a while, much longer than I think I could have, and you certainly can't say you haven't tried. I admire you for sticking with it. However, I think if you did put things in perspective, upi might find that seeing each other 3 times per year and talking for 4 hours per week is still definitely keeping in touch. Many of us who have lived with LDR have had to deal with less contact than that. It's so much harder to keep those you love close to you when you have classes, work, and your own family and friends to attend to, as well. I know because I have been there. I was taking 4 graduate classes at once, plus working nearly full-time before I moved here to live with my (now) husband. There were many times when I wanted to be on Skype with him for hours, but had to cut it short after half an hour because I had several papers to write. It hurt to have to push him aside to do all of those things, but it was what I had to do. There were times when I was working a double shift and would race home in between the shifts (a 20 minute drive each way) to just see him for 15 minutes on the webcam. My DH (then boyfriend - fiancee) was working overtime to save money for the visa and the move and trying to find a place for us to live and all of that stuff. It was very stressful, exhausting, and heartbreaking for both of us at times. Schedules often conflict because of the time difference, which makes it difficult sometimes to spend as much time talking to the one you love.
I do agree that communication is extremely important in an LDR, otherwise someone may start to feel neglected (as you do now) and things can start to fall apart. Insecurity creeps in a lot in LDRs because you don't have the comfort and reassurance of daily contact and physical contact and all of that. I agree with the others that you should tell him the severity of what you are feeling right now. It sounds like what you need is a commitment or plans to move forward, because at the moment, things appear to be taking so long that you are getting frustrated, and I certainly don't blame you there. But if he is working, studying, and trying his best to move forward in his career for the reasons you said - so that you can be together and have the life you want, where he works and you stay home - then it may be understandable that he is so busy and trying so hard to do that, that he is missing the fundamental reason for doing it, if that makes sense. If he is doing all of this for you, then you must never forget that, and he should make sure you never fall by the wayside or feel neglected because of it. If you keep reminding each other that all you are working toward will pay off in the end by the two of you being together, then you can keep your relationship alive.
But it's really up to you where you go from here. If it's just taking too long and you feel yourself separating and starting to move on in your own life, then it may be best to end things. But if you talk to him and tell him exactly what you are feeling (as others said, an email or hand-written letter might be best so that you can be sure you are getting all your thoughts out there) then maybe there is a way to bring you closer together and back on the right track. Good luck either way.