Help with housebreaking a small breed dog. PLEASE!

Hello! This is Riley . ( Sorry its so long I just want you to have all the info)

I just adopted her from the humane society a week ago. She is 9 months old and that is the only info the previous owners gave them. She is my first small breed dog, and is partially house broken (if that is a thing). But I am finding it a lot more difficult to housebreak her than the other large breed dogs that I have raised in the past. She doesn’t let you know she has to go out, so right now we are just going off of her “tell”. When she starts sniffing the carpet we know its time to go out. We also have a kind of schedule with her. She wakes me up at around 5–5:30am and I take her out right away, she normally pees immediately and then takes about 20 minutes to poo. Then the outings the rest of the day are kind of frustrating. I take her out about every hour and about a half hour-hour after she eats (just like the sites I read suggested) but we will be out there for almost an hour and she wont go. Then when I bring her in she’ll go on the carpet. Some times she will actually go while out there but not till about 15 mins after we’ve been outside, she’ll go pee then wont poo for another 15–20 mins later. I praise her when she goes and give her a treat right after shes finished with each one.

I just don’t get it, why does it take her so long to go initially and in between and how can I break her of holding it till we come back in? I mean I will sit out there for hours waiting and nothing then come back in and she pees… PLEASE HELP!