Still unsure!

I was supposed to get my period on the 14th and it was late so I took a test on the 19th and 20th, both test come back negative! I thought I was fine and that I was not pregnant and I was so late due to smoking weed for the first time in a year on the 12th. I ended up getting my period on the 26th (12 days late) but it has been extremely light and I had very intense cramps the first couple of days. So I don't know what to think. Can you guys give me your opinions please? Btw I have been consistently having sex with poor condom use . We have been putting it in for a few minutes with no condom then finishing with a condom.