Hi, welcome to HCM I am Dr Das
First of all, don't panic . As you told you have done us which is normal is a definite indication that there is no pregnancy
. Us is the highest diagnostic tool. So, you are not pregnant.
So, what is it?
It is nothing but the sideeffet of the i pill
. You periods will be regular within2 month. If not, consult gynaecologist for suitable cop which will normal your periods.