Hi A. and congrats on the two young ones (so close together, you are quite brave). I would definitely take a home pregnancy test. It very may well be just an irregular period, BUT tubals are not 100%. I am a nurse in an ER and in the last year alone (since i returned from my maternity leave in April), I have taken care of two patients who had had tubals but found out they were pregnant.
Also important to determine now if you are pregnant is because they sometimes become tubal or ectopic pregnancies, which if left untreated can rupture...
good luck, go buy a test, and if you are pregnant make an appointment with your ob. if you have any questions, just shout out!keep us updated.