Its natural to have sexual thoughts and to masterbate. Some people do become addicted to sex and masterbation but thats not to say that you are. Perhaps you could try cutting down a little one day at a time and see how you feel. If you still feel that its affecting your life in a negative way you might like to try talking with a trusted person.
There's nothing wrong with the cravings! It's natural to feel that way and have those thoughts during the day and to just take a peek sometimes. If it's effecting your life, then it's time to try something different. Don't be embarrassed by all of this. Your friends are probably experiencing something similar! Trust me, I have my days/weeks/months where I feel the same way ;-) I've masturbated with friends, guys and girls, but I just kinda forced a situation where the topic came up. I didn't just bring it up out of nowhere. That would have been awkward. You have to feel them out before you drop that on them lol... you can message me if you want to talk more!