Zepbound and my potential period questions

So I've decided to officially start on the 2nd of next month for reasons and to help prepare myself mentally, I've done a bit more research on the beginners guide like you guys recommended and I found out that the shot lowers the effectiveness of my birth control pill?? This is concerning me because while I'm not sexually active, I do take the pills for my very heavy periods and have been taking them since elementary school. Like, I will easily bleed through my pants if I'm not careful enough. I also possibly have PCOS due to my irregular periods, acne problems, etc. but I've never been officially diagnosed. I've been privileged enough to not really need to pay much attention to the length and times of my cycle due to the pill but now I'm scared of the massive change. I'm also exclusively a pad girlie and can't use tampons or any other inserted devices due to my vaginismus, if that means anything to you guys.

I've found some older posts talking about these kinds of symptoms of the shot and, while I'm thankful I'm not alone, I'm very nervous about what's to come due to how common it is. I think this may just be a question I need to ask my doctor but for now, any advice or comfort would be greatly appreciated. Thank you guys so much for being here.