first time iui estrogen plateau??

Heather

m on CD 11, took letrozole from cf 3 to 7. had an ultrasound on CD 10 that showed a good size follicle on the right and left and no surge in the bloodwork yet. blood work today showed my estrogen has plateaued so i need to go back tomorrow am for another ultrasound and more blood work. has this happened to anyone else? what does it mean? what was your outcome? any advice is appreciated! I'm a wreck over here.