6 months in and our adopted dog is still peeing inside

We adopted a poodle cross approx. 3 years old 6 months ago. The shelter had no history to go off. She was very shy, reserved but has definitely come out of her shell recently. A very lazy girl though who loves the couch. When we first brought her home, she refused to or outside. We would take her outside for an hour + without any toileting, as soon as we would bring her inside, she would pee immediately. She hated the grass so we focused on her going on our bricks. We tried fake grass, puppy pads, everything to see if she was used to a different potty spot before adoption. Eventually we we got to the stage of her going outside with lots of praise when she does go outside. I hate to discipline her due to her timid nature and the fact that any loud noise or sudden movements causes her to jump and stress.

A bit about our situation: we live on a farm and have another poodle cross, 3 years old. We have a doggy door leading into our laundry, which then leads to our house. It took a bit, but the new dog is comfortable using the doggy door to go in or out when she wants. If we don’t want the dogs in the house, we will simply lock the laundry door so they can still come inside for food, water, bed etc. in the laundry but not free roam the house. I would love to get to th point of being able to leave our new dog free roam the house when we are not there. We do not want to crate train due to it not making sense for our situation. Both dogs are relatively calm and we are happy for them to chill on the couch when we are not there.

However, our issue for the past few months, which we cannot seem to get past, is that our new dog will not take herself outside to go to the toilet. Currently, we take her outside every few hours or when she starts to roam, and she will go toilet outside and come back inside when she is finished. However, if she needs to go and we don’t take her outside in time, she will just go on the carpet. We ultimately want her to take herself outside via the doggy door.