I've been lifting about 3-5 days a week since I was 14. You will be fine. I am short (5'8" or 5'9") but that has nothing to do with lifting. My dad is 5'8" and my mom is 5'2". I have a very short and stocky family.
If you want to gain weight, I don't recommend Creatine or a muscle building supplement. Eat a lot, and if you must, use a high calorie shake like "Weight Gainer 900". That's what I use.
