As long as you have the support of your family and his, then it shouldn't matter what others say. And being 17 and pregnant isn't as shocking and disappointing as like 14, 15 year olds. You're practically an adult or will be at 18 so it's not that big of a deal. I think it would be much worse for you if you didn't have the families behind you, cause then you'd feel a lot more alone in this. But that's not the case, so it's going to be fine.
If your family knows and his family knows, hold your head up and walk through it, even if it is hard at times. Parenthood *is* hard at times. You got pregnant, you probably weren't trying to, but you are still a proud person who keeps herself together, I assume.