Do I need Help

[The dirt bird]

I Masturbate nearly every hour if I get a chance, I'm never off the internet looking at porn sites and masturbating, if not at that I having it off with the sex dolls and then when the GF is home weekends, I'M on her too and think she's glad to be going back over to college.
With all this going on, my studies are suffering badly, i cant concentrate on them and only think about naked mature girls and what I could do to them.

You need to distract yourself till the urge passes take it one hour at a time. You may be stressed and excessive masterbation might seem like a release but it is causing you more problems than it is solving.
It's not good for self esteem, mental health, relationships etc
I would not be to concerned if you have a high sex drive when your gf is with you as sex is really very good for you and don't beat yourself up over that but the excessive masterbation is a problem you should speak to your gp about and believe it or not you won't be the first ! Many guys have the problem you are describing and it usually (not always) is linked to anxiety disorders which are very common in college due to the stress you guys are under.
Good luck walshie.