You can be late from numerous things. I missed a whole month one time just due to stress. I wouldn't worry. You could always go have a blood test done and that would let you know for sure, no ifs, ands, or buts. I don't think I have had a normal cycle yet since I have had my son. Lol. And if you just had your tubes tied 8 to 9 months ago then your body could just be still adjusting. Well keep us posted and I hope everything works out for you!
if your test came back negative then i wouldn't worry... your tubal would be effective immediately so even if you just had it done you should be fine!