Thanks for your query.
It is almost impossible to conceive, while you are having your period.
However, there are cases reported, although rare.
Also, since your periods are irregular, your ovulation also would be erratic, which is all the more reason for you to use protection all throughout your cycle.
You would not be able to take a pregnancy
test reliably, as on account of the irregular cycles, either a positive or a negative result would not hold much relevance.
You have to consult a gynecologist who would rule out a pregnancy, and also provide you guidance for the irregular cycles.