Ay, mama, that heaviness and pulling sensation downwards is actually pretty common, a few of us felt the same thing, lalo na pag tumaas ang baby or ligaments are stretching, pero yung stinging pain na radiating from your belly button, hindi naman dapat nag-worry kayo pero mas better kung i-check ninyo with your OB just to be sure, kasi there are so many things it could be and iba-iba din per person! Let me know what your doctor says, ha.