HELP!

A

I had a baby 3 months ago and got my 1st period back on the 6th December. I am due on again however I am now 3 days late. I had sex on the 25th December but the condom split what are my chances of being pregnant? I don't kno2 how long my cycles are and when I will ovulate because they was never regular before I had the baby and I have only had 1 up to now so can't work it out!