Switching to new bc pill

So 5 weeks ago I recently stopped taking a bc pill brand to switch to another brand. I have not had a period in months while I was on the other brand. Dr. told me to start taking the new pills once I start period. It’s been 5 weeks and still nothing. This might be a stupid question but I’ve never had this issue before. Wondering if it’ll be ok to go ahead and start taking the new pills? Has anyone else had this problem? I’m just ready to start taking them to avoid getting pregnant.