With so many repeatedly negative urine pregnancy
tests, the possibility of pregnancy is rare added by the fact that failed sterilization
does not show so soon. It is more likely to be the hormonal
imbalance secondary to the delivery and also to tubal ligation
. Weight changes and the stress of delivery also play a role. If you still wish to exclude/confirm pregnancy, you can go for the assessment of the serum beta-hCG titres along with a trans-vaginal sonogram and a specialist opinion. Hope this helps.