IVF & Slow Estradiol Levels

I am currently undergoing IVF in Canada.  I have about 24-29 follicles and they are growing nicely and are all around the same size- 15.8-17.6 mm. Tonight will likely be my last stimulation injection with an anticipated trigger tomorrow night.

Apparently my estradiol levels are progressing a little slowly. That was the reason why they had bumped up my meds from 150 iu of Bravelle to 225 and then 300.

I think my estradiol was about 584'ish on Monday (after four injections,) 1555 On Thursday, over 3550 on Saturday and 6668 Yesterday, Monday.  Keep in mind these are Canadian measurements, divide by 3.67 for the American equivalent.

Apparently they like to see about 1000 units for each mature follicle...

I've only talked to the nurse, but she mentioned that eveything is okay, and not to worry. Of course I am!

I don't know much about estradiol, does anyone else? Should I be worried?  Does this mean that most of my follicles do not contain an egg?

I was reading that some people say it may be better to give your injections in the belly rather than the thigh... better absorption or something? I'm overweight so my belly is a little more "fluffy" than my thighs... does anyone know if that makes a difference? Should I be worried?

I've read that estradiol levels are lower in overweight women... how much lower?