From a coach's point of view: remember why you play football.  Your problem appears to be less about skill and more about your stress. 
 
Beyond practice; pick an upcoming game and beforehand decide you're going to go after the defender every chance you get. Explain this to your coach and let him/her know so you have an ally. If you are a forward, this should be expected.  In fact, I will even advise you to lose the ball the first few times. How? Allow yourself to just experiment and hold up the defender - don't over-think it. The only skill advice I will add is be good with both feet.  

Get the defender out of your head.  Smile; be creative fluid and fast.  Once you've lost a couple of battles (and likely won a few), keep going after them. Once the stress is gone, you will enhance your team.  You have to want the challenge.