It's the old green eyed monster at work and you look for evidence to prove your jealousy right. It sounds to me like you have exhausted all possibilities and the problem is simply you won't trust him.
Tell me, when wuld he get a chance to have another girl? You're there all weekend and talking to him all week.
He's right, you are interfering with his studies and if you continue you will make a breakup a self fulfilling prophecy Of your making.
There's a hell of a difference bewtween maturity in ages 23 and 18. That's more than a quarter of your life.
It's my feeling you have already gone too far, initiating arguments and checking everything he does. Trust is a key ingedient of any relationship and it's about time you starting practicing it.
Yes, seeing a doctor will lead to a therapist but all they will tell you is you have to trust him or you will drive him away. Go ahead, do the doc/therapist route and find out I'm right.
It's only a short time before you start watching his eyes when he's with you to see who he's looking at, or are you already there?
Calm down, you've proven he's genuine, let's hope it's not too late to fix. Trust him and change your jealous ways. Or you know what's coming. Tell him you know you're wrong and you will stop. And do so. Else.....false promises lead to no boyfriend.