Am I wrong? (kind of long)

lightheaded1der

So after about 15 positive HPT's on and around Mother's Day, I called my gyno and she made an appointment to go in. I figured the appt. would just be to do a blood test to confirm pregnancy. When I got there, they asked a surprising few number of questions, including first day of LMP. I told them April 15th, so they told me I was 5 weeks based on the little due date wheel they use. I took the time to make sure and tell them that I have long cycles (I O'd on cycle day 19 or 20 per FF, which is actually early for me) so I actually thought I was more like 4 weeks.

Anyway, the gyno insisted I was 5 weeks and 0 days and told me that we should see something on an ultrasound... she saw nothing. She told me not to worry and that maybe I had my dates wrong or the baby was in a hidden spot. Then, she sent me to get my betas.

 I have already decided to switch to a new gyno at this point because she didn't send me home with ANY instructions about what not to eat, etc. She basically acted like she didn't believe that I was pregnant. The point of all this, and my question, am I thinking about EDD correctly? Doesn't calculating based on LMP assume you have 28 days cycles? If so, shouldn't my gyno know better?

I am freaking a little about not seeing even a sac at what I think was actually closer to 4 weeks.