Easily overstimulated?

My pup is 4 months (standard poodle) and I raise her alone in a “beige quiet home”. Im very calm with her, very structured, very type A person. I pretty much follow a schedule of 1 hour awake 2 hours asleep. She sleeps through the night. She has been very good with me, understands commands and structure quickly. She sometimes jumps up on walks (biting the leash and my jacket) but I took it as puppy behaviour. I enrolled in individual training (wanting to be a responsible owner but also thinking idk if she even needs this). First session went horrible – ive never seen her this. Nippy, jumpy, overstimulated. The session was outside in a place we go for walks. People nearby. Today was our second training and i made sure she slept enough etc and same thing. She couldnt even walk on leash for 5 meters. She would start nipping and jumping at the trainer constantly. Not possible to lure her in with treats, or get get to sit etc. Trainer also seemed a bit baffled? Did anyone experience this with ther poodle pup? What to do in this situation? May this be caused by “new people – trainer” excitement? Am i causing this by my beige quiet home approach?:/ Im not exposing her to “the world” that much i guess. Lot of training is done at home and we do about 2 walks a day. She didnt meet that many people yet, is that causing the overstimulation? What to do please 🙁