I am about to do that to my little female 10 pound dog.
I will take her outside and she pees a little here and little there. She is more worried about checking everything out instead of peeing. Then I will bring her in and 10 or 20 minutes later she pees on the tiled floors (never the carpet).
She gets crated at night and will not pee her crate, so I know she can hold it and I take her outside as soon as I remove her from the crate. I walk her for 20 minutes to 30 minutes.
She was a rescue dog and I adopted her when she was 5 months old but she was in a crate mostly during those 5 months.
She has sweatshirts, coats, t-shirts, etc to keep her warm while we are outside in cool and cold weather. She loves to wear her sweatshirts and gets pissed off if you take them off. (shorthaired little 10 pounder who has to have clothing to keep her warm. I cannot stand to see a dog shiver)
Anyhow she is about to be diapered as I have to take her out about every hour for about 10 minutes and still she pisses in the house sometimes.
Trust me... baby diapers are so much easier on everyone. Our "problem" dog was a show dog and ten months old when we got her.. she was crate trained and you know what that means.. same thing you are seeing. The best brand I've found for the dogs is the LUVS. We get them at Walmart and just below the velcro band cut a pear-shaped opening so she can poop (she will go outside for that) and it catches the pee.. you'd be amazed how much they hold and dont' get the dog we and no smell on their skin.
I do cut snips just below the velcro strips, it allows me to make it a little more snug around the waist while making it more comfortable around the leg area.
IF every dog trained like our Daisy (showed her once and she was trained) there would be a lot less dogs turned into rescue over potty training issues; baby diapers could save a lot of grief for everyone...
We do take them off when we put her outside to go with the other dogs, and she is getting it.. but when it rains, she will not get wet and on goes the diapers. Helps when you travel and have to take them to a hotel as well.