Its best to go and see your doctor, sometimes after a few years the tubes can fuse together and you can become pregnant again, my aunt fell pregnant 2yr after she had her tubes tied so it can happen
It's always possible. Since you're late, a pregnancy test should show. Take one with first morning urine and see what it shows. You could also talk to your doctor and request blood work be done. If you are pregnant, they would need to see where the egg implanted. Risk of ectopic pregnancy increases by 33% after tubal ligations are done.
I have heard after your tubes get tied that your tubes after a while can reconnect. Did you get them burned or just tied? My mother got her tubes tied, 5 years later, she had her AF one month for about 3 or 4 days, and found out shortly after that she was pregnant. It maybe hormonal changes or maybe preg. The best way to check is a HPT. And it that comes back negitive then go to a GYN and have some bloodwork (if you feel this is necessary). Best of luck to you