you almost certainly didn't get pregnant the first time on 26 March, because you took the I pill
on time. the period you had afterwards and the unusual pattern of bleeding that you describe are almost certainly due to the I pill, because the I pill often causes that problem. however, after a few weeks, your periods should return to normal.
however, the second time you had sex, in April 7, it is remotely possible though extremely unlikely that you got pregnant. the only way to know would be to wait until two or three weeks after you had sex, and if you still don't have a period, take a pregnancy
test then. if it is still within 72 hours of having sex, you can still take the I pill again to prevent pregnancy. if it is past 72 hours there is nothing else that you can do except wait until you confirm the pregnancy at which time it will be your choice if you want to terminate the pregnancy or carry it.
he most important thing is to get started with regular birth control so you can stop worrying about these things so much. so talk to your doctor and find a birth control method that is right for you.
I hope this is helpful, please let me know if you have any more questions.