I'm 14 weeks tomorrow and I've actually lost 2 lbs per the doctor's scale, but stayed the same according to my scale.
This is my second pregnancy and I feel like I'm 5 months already, not just 3.5! It's true that your body has already stretched out before so it doesn't have to do all that work again, so you pop out earlier.
Did your different doctors do your dating based on u/s? It seems odd that they would be chaning dates. Do you not know the date of your last menstrual period (LMP)?
I'm there with you feeling like we just hurry up and wait... wait for the pregnancy test, wait for the first doctor's appt and u/s, wait for the level 2 u/s, wait to find out the gender, wait for test results, wait for labor to begin... wait, wait, wait!!!