Is it normal to be very nervous/anxious/stressed?

I get overwhelmed easily with situations and seem to get very stressed out in regards to getting everything done on time and everything feels like a conscious effort. In social situations i can sometimes be very nervous and then think about the fact that i am nervous and this makes me act strangely sometimes and very anxious. It is very annoying and i have tried alternatives to help stop feeling this way by reading books to gain information on how to combat these problems but they still occur. I find it very hard to relax and feel loose around anyone but my mother, i wish i wasn't this way, do any other geminis feel tense a lot and stressed? I am quite worried about developing a nervous illness or something along those lines as i have already developed rashes on my skin due to stress and i'm not even twenty yet, just turned 19. This is worse when i am single where as in a relationship i am much calmer. At the moment I am single feeling very restless and stressed and tense at the moment. If i stay in the house for a couple of days or do not talk to my friends for a few days i can get very down and lonely and start to feel quite insecure and paranoid when leaving the house to do simple things like go to the shop. I came out of a relationship six months ago which hurt me very much, i think he was a sociopath and has sort of scarred me a little bit i still miss the few good times we had and the company but would never go back there as i know it would just get more and more painful. I still love him but i know he is no good for me and even though he calmed me down, i was crying more than happy and fed up of being accused and manipulated. I have always had these feelings since a young teen but just seem to hate being single as well. I don't know if this is normal behaviour but it sure is annoying for me sometimes.