Usually acting like you dont want or need sex is a sure fire way to get it. Whenever I have the intent of fucking I never get it, and when I don't care I always get it.

Not sure, I would just write hey trouble or something custom based on her profile

Personally, I wouldn't have said what you did about being average, seems like you are trying to justify and qualify yourself as being average saying that your average dick still causes a girl to cum; should go without saying.

Could have said something like "That is something that can be up for your interpretation" , something along those lines without admitting being average and leaving mystery. If no response in like a day or so I would follow up with: If you're into that sort of thing