first time puppy owner in need of help

My boyfriend really wanted a puppy. He doesn't have much dog experience, and I only have some experience with dogs who were a few years old and already trained. I'm regretting getting her, and he insists she will be fine when we start having children. We're planning soon. I'm so scared she is going to hurt a newborn or any child.

My samoyed is 7 months old. I have no idea what motivates her. She is not food driven. She doesn't care for praise or affection. We've had her since October.

I plan on getting a trainer after her spay. She is very distracted outside and will not listen to anything. I've tried the stop and go method, reward her for being calm. It was working until she figured out if she pulls and has to stop, she gets a treat. I've stopped the treats and she gets frustrated and will jump up and try to bite me while growling. She will not stop. I don't know what to do in those situations.

She's doing better about going outside to relieve herself. She let's me know when she wants out with a bell on the door. She has the odd accident.

I want her to have dog friends, but everyone I know has a small dog. She just wants to run up and bark excitedly at them, jump on them. It comes off aggressive when she's just very excited.

We took her to the vet last week for her shots. In the waiting room, she barked so much just seeing the receptionist. I tried to distract her with a treat and she ignored it completely. It was embarrassing. We live out in the country and there is not a lot of opportunity to meet new people or dogs.

When we try to pet her or give cuddles, she keeps putting our hands, arms, or face in her mouth.. she doesn't bite hard. I just tell her no and give her a toy instead. She will spit it out and continue to mouth on us.

We have a few cats who mostly hide in their cat tree. When my bf holds one for her to meet, she sniffs them a lot, barks in their face, then tries to bite them. When she starts to bite, we put the cat away.

When my boyfriend's niece comes over she jumps up , barks and bites. She already bit his dad. It doesn't seem aggressive, just way too excited.

Any videos I watched on training, they bring out an already trained dog.. the methods they show just don't work on her.

We go out for long walks everyday (weather permitting), play with her inside. I had hoped I could bring a dog to the hiking trails we like, but I just can't with her.

What can I do about the biting and over excitement? Or when she decides to jump up at me on walks?