Hi there, I have understood your concern. I will suggest you the best possible treatment options.
1 ) First of all do do not panic.
2 ) Even if you have irregular cycles, there is always a risk of
pregnancy with unprotected sex act.
As you have mentioned that you have taken a pill after that sex act , I suppose it was an
emergency contraceptive pill.
If this pill is taken within 72 hours of unprotected sex act, it works to prevent the pregnancy in most of the cases.
3 ) If you have crossed 20 days past your episode of sex act, I will suggest you to get rid of the pregnancy dilemma.
Please get morning's first sample of urine tested for pregnancy. In case of doubt blood
beta HCG test and USG will be of help.
4 ) I will suggest you to get proper sex
counselling done. Use of suitable contraceptive method like birth control pills, will help to prevent unwanted pregnancy and will also regulate your monthly cycles.
I hope this answer helps you.
Thanks.
Dr. Purushottam Neurgaonkar. .