I'm ready to pull my hair out. Reina cannot go for a walk with her leash without pulling full force, or jumping up and biting the leash and jumping on me in the middle of the street. Telling her no/down does not work. She knows both those commands but ignores me. It is so frustrating/embarrassing when I am trying to walk her and she attacks me out of nowhere! She may be only four months but when she jumps on me she leaves all sorts of cuts/bruises. Shes a solid one! Any way I can teach her not to do this?

What are you using to walk her with?

just a collar/leash. I keep forgetting her harness at my boyfriend's.. you think that she would behave better with a harness?

No. I don't. Some will say a harness encourages pulling, it's not true. It simply makes pulling easier/more comfortable. I never do training in a harness, just a flat collar.

There are many methods to teach loose leash walking. Treats. Praise. Prong collars. Slip leads. Various forms of correction. It's all up to you what you want to use. I personally used a combination of teaching methods. You can google on to teach it. The biting, jumping, pulling, and otherwise obnoxious behavior is quite normal/common. You just have to teach her.

How we started: 30 foot leash, in a large park. No distractions. You walk a square. One side at a time, then pause at the corners. No talking. No praise or correction. Then say 'let's go!" and walk the next side of the square. About 20-30 paces a side. Your dog may run to the end of the leash and get quite a jolt. Don't prevent it. She needs to learn to stay close to you. After you can walk the square without a tug you shorten the leash a little and go again. This was a few weeks worth of work. Not an overnight fix.

As for walking you can't let the pulling get her what she wants. I'd start with just the squares and avoid walking until you can get her to follow you rather closely. Set them up for success. If you want to walk her take treats and praise and treat whenever she walks well. If she pulls, jumps, or bites, you must freeze. Become a tree. Ignore her until she settles down. Start walking again. If she behaves. Treat and praise. Of she doesn't. Freeze again.

Walking is a lot of work. We spent many a 30 minute walks barely moving 100 feet.

Also, Regarding the square method. You'll probably have to start at the full 30foot length every time you start even though she may have walked great at 6 feet by the end of the last session. You'll just progress faster the second, third, fifth, 20th time until she has it down pat. Then try starting at shorter lengths.

If she ever gets obnoxious at a shorter length you've moved too fast. Make the leash longer again.