I need some advice/help to become the owner my new puppy needs me to be.

I did my research and got all the stuff I need for her already, but I am still having a lot of trouble with training.

For context:

• First-time dog owner
• I've had her for a couple of weeks now.
• She is a full Pomeranian 3.5 month old puppy.
• She knows how to sit, but can only do it when I have a treat and holding it high, not sure how to fix this.
• She’s having trouble with recognizing her name, sometimes she does recognizes perfectly, sometimes she doesn’t, outside she doesn’t at all.
• When outside, no control over her. Super reactive, scared of other dogs, keeps pulling, wants to do her own thing 24/7.
• When inside she’s a little calmer, but sometimes crazy. Biter and a jumper.
• She’s somewhat potty trained. She knows to pee/poo outside and pee on her pee pad, but sometimes she pees on door mats.
• She’s crate trained perfectly.
• Not sure whether she is food-motivated or toy-motivated, she shows the same amount of excitement for both. Sometimes it alternates, might stop wanting toy or vice versa.

That’s all the problems we're having right now, and would like to fix them.

I was also thinking of whether if I should go back to square 1 and reteach her everything as if she were a 4 week old puppy? If you think I should, what should I teach her in order? And how can I do it properly? (Any recommended videos, books, sites, etc.. are accepted)

I want the best for my pup, but that only happens if I become knowledgeable in nurturing her to become an amazing doggo, that’s why I’m coming onto here to ask for advice.