My puppy is terrified of outside

I have a super sweet 3 month old German Shepherd/Husky mix.

I just got her last night and wow was this a doozy.

She hates outside. She hates her harness. She will bite the sh*t out of me trying to get it on. When I try to take her outside she is petrified. Shaking and to the point where I have to physically pick her up. And when she is set down she immediately wants to go to the stairs and back inside.

She is not potty trained so it’s been a nightmare. Enticing her to go outside is its own problem so tackling potty training is a complete conundrum.

I also unfortunately live on the 3rd floor so I cannot just get her outside immediately if she’s mid pee. She also has no tells for peeing – she will just squat and G O.

It’s wearing on me and I’m completely overwhelmed to the point of tears.