Separation anxiety??

So let me start this by saying that I have been diagnosed with anxiety:
Lately, I have been extremely stressed and extremely anxious when I'm not with my boyfriend, we've been together for about a year now but I've just noticed this anxiety within the last month or so (this may have to do with the fact that he went to a party a few months ago and another girl pretty much threw herself at him and he waited to tell me until last month). But When I'm with him all my anxieties go away and I truly could not be happier. But then when I am away from him all of my anxiety symptoms come on full force. Even taking my anxiety medication that I hate does not relieve my symptoms. It's not like I don't keep myself busy when I'm away from him, I have a very active social life, I work 2 jobs and go to school full time. 
I'm just so confused and tired of feeling this way. I don't like to be that girl who NEEDS her boyfriend.. But it's almost painful for me to be away from him. 
Has anyone experienced this before? Any insight or opinions would be VERY appreciated!!