How fast is too fast?

I know all relationships are different; each go at their own pace. My boyfriend and I have been dating for almost 4 months now and we're saying I love you, we can both see a future with one another and we're pushing each other to do better. We had sex after our second date, but we'd talked for almost 2 months before finally finally going out. I didn't think we were moving quickly until my friend said it was too fast. So now I'm confused.

He's 21 and I'm 19 if that matters.