WHATS THIS IN MY PERIOD?

So I stared BC about just over 6 weeks ago, and I am still on my period (for 6 weeks😳). I went to the doctors and switched over to a different stronger pill. And since then, I've been getting more string like blood clots and small clots that look like tissue/skin. Is this normal? Or am I having an early miscarriage or even pregnant!? I'm 17, unsure and worried. I've never had skin like clots before