Rescue dog holding her pee?

Hello, everyone! Crossposting for more advice!

We brought home a very sweet 3 year old chihuahua on Wednesday! She is an absolute angel, but she has very clearly been through some major trauma. She was a surrender by her family as her original owner just passed away, she had also just given birth (our girlie, not the owner).

We are so proud of her as she has been blending into our little family incredibly well, but we are very concerned that she is incredibly co-dependant and also seems to hold her pee until she finds a sneaky spot to go.

I am very diligient with watching her and bringing her out every 30 minutes to an hour all day and so far she has peed twice outside and pooped 3 times, but for the most part every time she is out even the slightest sound TERRIFIES her.

I know she has to go because she will start sniffing, but once a sound happens she changes are mind and wants to be picked up again. She also will not walk. At all. I try putting her down and she will immediately walk over and start pawing at my legs to be picked up again, so I've had to just slowly keep scooting around to try and convince her to sniff. This works maybe 1/4th of the time and often we just end up outside for 30 minutes scooting in circles.

I have now found 2 small secret pee spots she somehow managed to use, a towel and her tiny blanket, which is crazy because she only leaves my bed when I take her out so I have no idea when she found the time. The rest of the time she spends under my blankets and does not want to come out.

Has anyone navigated this before? It feels like a confidence issue, but I'm not sure how to help her. We bring her out very consistently, throw a whole party every time she successfully goes, and ensure she's always getting love and high value treats! I'm just so worried for her as I can't just carry her forever and we definitely don't want her to form a habit of sneaking to pee everywhere.

Any advice is greatly appreciated 🙏