​I screamed loud and felt a slight pinch in lower right tummy area next to my new belly button. Do you think I ripped stitches?

You don't say how long ago your surgery was, but in my experience, it would be very unusual to rip the sutures, especially just by screaming.A pinch sensation in your abdominal wall could be anything, but I doubt that you have ripped any stitches.  Nonetheless, you should ask your surgeon if you are unsure.