What you should do now is consult a specialist (a gynobs is of choice) who can reexamine you properly and run a pelvic scan (which will immediately tell what is going on in your stomach). Abnormal intrauterine growths/masses/tumors can mic mic signs of pregnancy
and hence reason why you are lactating and stomach swelling.
Now let talk first of the most likely cause of your symptoms, that is pregnancy. It has to be ruled out again with gynobs. Detachment of tubal ligations (especially depending on the method that was used for the ligation) can occur in a small proportion of women especially after a while. I suppose you have been sexually active and if you are experiencing signs of pregnancy it simply means that you are pregnant or having hydatiform mole???.
So your next step is do a pelvic scan after being examined by a gynobs.
Hope this helps