I'm ruining my own relationship

ok...so ive been with this guy for two years..n hes a nice guy...bt the problem is i can get very moody and obsessive about him...things are always fine until i get a mood swing...hes 24 and im 20...he works n im a student...so i have alot of free time..he doesnt...n its just so hard for me to understand that...n when i have nothing to do...i piss thee hell out of him...i repeatedly call him wen hes busy...i call him so much that he ends up turning off his phone..bt its annoying when he doesnt return my calls...he ll call me in the night before sleeping..he doesnt respond to my lovey dovey msgs...sometimes he does..n if i call him 10 times..he ll call me just once...i know this is a small issue bt why cant he just make time for me..there are so many small issues like this which totally confuse me about this person...n hes stubborn by nature...n wen im moody..i send him these very rude msgs which would totally crush a person...he ignores them but after a point he gets angry n his phones off..n i hate that..! basically when we fight...i need to talk it out with him n solve the problem bt he needs his time...i know hell call me if i just leave him alone but i just cant stop myself from calling him a million times in an hour...i have all these weird thoughts about him talking to some other girl and etc etc..even though i know he wouldn cheat on me...cause hes so busy that he doesnt find time for me only...what do i do...i cant stop myself from being obsessive bout him...i dont give him enough space...i dont give him a chance to miss me cause im always calling n texting him...i hate this...i want to change but i just cant...