Full blown period while on BC?

Hello Glow, I take Tri-Sprintec, right now I'm on the week 3 row and this is my first time taking Birth control ever.

Mid to late week 2 I had some spotting and it just got WORSE. Now I'm still taking the pills for the birth control but I have a full on period and tomorrow ( Sunday) I start my "period week" sugar pills.

I've never missed a dose, and I take the pill religiously at 12 noon everyday.

Is this normal when just starting birth control? Like does the body have to adjust to it?

My doctor told me if I had any sexual encounters within week 1 to use another form of protection.

I had unprotected sex with my SO in week 2 before the spotting. Could that have caused the problem?

Sorry if these questions sound weird this is my first time taking birth control ever and I am clueless.