I'm feeling heaviness in my lower stomach and tenderness is that a sign of ptegnancy?

Menstrual period. Lower abdo pain and fullness could be pregnancy, have you missed a period? It can also be a bladder or vaginal infection. Constipation also causes lower abdo pain.
Possibly. If you were recently sexually active w/o protection, you could be pregnant - would recommend home pregnancy test for starters. If pain continues or worsens, or if you are pregnant, you should be seen by a physician for an evaluation.