Birth control question

So I have been on sprintec for months but it made me gain so much weight so I switched to lo loestrin just this months. I ended my my entire lay pack of sprintec and started my lo loestrine after I had my period. I was still bleeding a little when I started but I eventually stopped. I had sex after my period ended when I had just started the lo loestrin without a condom multiple times because he pulls out and the pharmacist and the doctor said I should stay protected. I google and checked with planned parenthood as well. However. Yesterday I was 13 days away from my period. And I had brownish yellow discharge almost like spotting. I worried about pregnancy. However I called and they said it could just be because I switched. I haven’t spotted at all today. Should I worry about implantation?

SOMEONE ANSWER ME!