Penis size isn't your issue here, forget about it completely. You need to be confident, don't be scared to approach women. Even if you feel like you may be rejected. You have to really make an effort and put yourself our there, because women will never make the first move or approach you. As a man, it's on you to do that.
Just to let you know about the things that women look for. Women are attracted to rich men, they have a real lust for money. Women are attracted to handsome, tall, rich men. If you are none of these things, then it becomes very difficult to find a woman to have sex with. If you're not handsome or rich, then you'll need other qualities such as a sparkling personality, high confidence and top notch conversational skills that enable you to smooth-talk your way into getting sex from a woman.
So here's what you need to do. You need to stop being shy, I'm sure you have nothing to be shy about. Why not invest effort and time into improving your image (sort out your wardrobe, get a haircut, stay well-groomed, etc), and try to expand your social circle by going out to meet new people. Don't be afraid to walk up to a girl and start a conversation, it may be very awkward, it may fail miserably, but you need to do that in order to get sex. Women won't give away sex just like that, you have to show them that you're rich/handsome/confident etc. Unfortunately, a lot of the time, it may be necessary to enter into a relationship before a woman will give you sex. In this case, tell her than you're also looking for a relationship, once you're in, you keep it going, get all the sex that you need, and eventually when you get bored you can leave her and move on to someone else.
Hope this helps. Also, don't let your life revolv around this, there are other more important things than sex (although perhaps very little else is associated with such a strong desire).
Good luck to you.
Posted from TSR Mobile