I'm doing everything before I should. a coworker is 3 weeks ahead and told me her doctor said I'm probably further along…

I'm doing everything before I should. a coworker is 3 weeks ahead and told me her doctor said I'm probably further along than I think. Now that I think about it I guess I could be, I tested sooner than I should have, my belly grew faster that it should have (I guess), I felt movement before I should have. But going off my lmp which isn't completely regular, 42 days and luteal of 21days, I'd be 16 weeks, the only sono I had I measured a week behind that, putting me at 15 weeks. I'm scared I'll go in for my sono and they're gunna tell me I'm further along that 15 or 16.