Opks not progressing?

So before i got pregnant in nov my periods were regular..about every 24/25 days. And would last about 4/5days. Anyway i mcd in jan and got my 1st cycle back on thursday and lasted 3days. I have been tracking with opks and on the 10th there was only the control line. And upuntill today a really really faint 2nd lime that doesnt seem to be getting any darker. Obs im at cycle.day 7 now so with having short cycles thats estimated ov date. Altho this app hasnt got me down till the 20th. Im.worried after the mc its naffed everything up.