How Can Pregnancy Be Confirmed?

Hi, im wondering whether I am pregnant or not. Its been about 4 weeks since my last period, i have had unprotected sex a few times since the last time i had my period. I am planning to take a home pregnancy test in a few days but im worried that what i am experiencing is unusual. I think I experienced implantation bleeding because it was not my typical menstual period. I didnt have any of my usual symptoms like pms and cramps. I had a very light spotting of watery pink blood for the first day and then it turned in to a very dark brown blood colour. The bleeding started 2 days before my period was due. The spotting lasted 5 days and now im experiening a small amount of yellow, thick, elasticity discharge. I also have a dull sharp pain almost an ache, sometimes feels like somthing is very tight and is being pulled in the centre of my stomach around my belly button and slightly above. Please confirm that what im experiencing is the early sign of pregnancy? And if i am pregnant, is what i am experiencing normal?