What are the chances that I am infected with something? Please Help.?

I have been seeing someone for almost a year. I am the kind of person that I get sick (flu symptoms, etc) and i immediately google it and then somehow, through webmd and similar websites, that I have some weird sickness and then i am convinced i have it. I tend to react this way in other situations, i get very anxious and over think normal situations to the point where it's almost obsessive. I took a cl on human uality and we did a unit on stds- I am now CONVINCED that I have every std in the book. My boyfriend has never had any symptoms, and I'm pretty sure I don't have any suspicious symptoms, but I think i'm starting to convince myself that little stupid things are actual symptoms. I have a slightly promiscuous past, but for the past year my boyfriend and i have not had any problems. I am scared to death i have every std and im scared to get tested, because if i do, then obv. my boyfriend probably has them too, and he will probably accuse me of being unfaithful and then god knows what will happen. I don't know what to do, it is driving me crazy and im scared to death and am losing sleep over it.