Estrogen falls, rises again about 7DPO then falls again. It doesnt rise as much as progesterone.

Check out wikipedia:
Luteal phase - Wikipedia, the free encyclopedia

This may explain why I simetimes get EWCM after O..... (just to add TMI )

Also from wiki:
During pregnancy, estrogen levels, including estradiol, rise steadily toward term. The source of these estrogens is the placenta, which aromatizes prohormones produced in the fetal adrenal gland.