Hi Welcome, I have a fairly new puppy also. I live in Ohio so I understand about the weather. When I got pixie at 3.5 months (December 1st) the weather was an issue but I am a believer that dogs do their business outside.
This worked for me – every 1-2 hours take the dog outside on a leash for a few minutes, when she went to the bathroom I would say “Go Potty” and give her a special treat/praise. And she could have free time in the house. If she didn’t go I put her back in her crate (were it was warm) and tried again about 30 minutes later. It worked like a charm. I do have a little coat for Pixie but I believe it’s for my benefit not hers. At this point, when it’s really cold she runs out, goes to the bathroom and runs right back in – less than 30 seconds. If it’s not so cold, we go for a short walk. Looking forward to spring!
This was a lot of work but I’ve had Pixie about 2.5 months and she goes outside faithfully. For night time, I did not give water after 8pm and last outside trip was about 10:30 and she was able to hold it through the night after about a week.
I am not an expert so I am unsure about the small 1.5lb yorkies. But Pixie is about 5lbs and much more robust than I ever thought Yorkies were.
I hope this helps, the people on this forum really helped me housetrain my puppy.
Good Luck and be patient, it works!