Possibility of pregnancy?

Got on depo on April 17th, 2018

My last period was May 23rd - 27th, but it was mostly spotting

I was due to go back for my depo shot on July 17th but I didn’t

I had unprotected sex on July 21st & 23rd

Although I haven’t had a period since coming off depo, is there a possibility of pregnancy? & if so, when should I test?