Potty training 9 month old puppy

So when I first got my puppy I was living with my mom at her house. We had access to a backyard and also trails by her house. He’s a mini dachshund so he had to potty every 30 minutes for months. He was doing so good he barely had any accidents inside and I was also consistent and on watch with him 24/7. He used a bell that hung low to the ground for him that he would ring when he had to go. But he would also just use it to go outside lol.

A little over a month ago, I had to move out for unfortunate reasons, and while I have been in the process my mom/sister have been watching him. Both of them are not reliable with potty training. But I’m taking him back in soon after I get my new apartment situated.

However, my new apartment had carpet, and my mom’s house was only hardwood flooring. So not only am I scared that he’s regressed in the potty training bc of my mom and sister but that the carpet will confuse him.

I just have so much anxiety about it because my mom’s dog has never been potty trained and I’ve heard dachshunds are really hard to potty train. I just feel intense anxiety about everything that’s going on all the time and it’s been making me feel like rehoming because my life has just turned upside down. But I don’t just want to give up.

I’m not sure exactly how I want to go about this. I’m gonna bring the bell to the apartment. My mom says he uses potty pads and that he’s probably only had 3 accidents since being there. But I never wanted him to use potty pads. Idk if I should bring them here or just cold turkey quit them. I can fence off the carpet areas. But how do I go about introducing carpet? Should I get belly bands or diapers? Or am I just overthinking.

EDIT: I also feel like I have to relearn his schedule or reintroduce my schedule because me and my mom have opposite schedules.