I need running advice/answers...?

Hey I've recently started running this past february and I must say that I love it and am improving every time I run. Although I love it, I am REALLY slow - even compared to my friends who rarely work out. This has me worried that theres something wrong with me. I have extremely short strides but I can go for about two miles without stopping. Im talking short strides as in a couple notches about speed walking. I dont tire too too easily but the thing i'm really worried about is my tiny stride. I've tried a few times to quicken my pace but then I get too tired and have to go back to slow mode. A mile takes me between 9 to 11 minutes and I weigh about 135lbs. Can you guys help me explain this or give any advice/recommendations? Could it have something to do with my diet? Or is it something physical holding me back? I really want to get good at running long distances but cant seem to break the cycle. What do you all think? Thanks a bunch in advanced!