I started my period on the 7th of december, me and my ex had intercourse on the 16th unprotected. could i be pregnant? my cycle is irregular

It is possible: It is possible, wait till your period is due and if you are late do a in home pregnancy test.

Pregnancy: Anytime you have unprotected intercourse, you have the risk of becoming pregnant or contracting a sexually transmitted disease.

Hard to say: With irregular cycles, it's hard to predict when your fertile time is. So the answer is that you could be pregnant, but more likely not.