Kam2490 your baby is still a puppy and this is pretty normal, happens to my 4 month old too.
When i stopped on a walk and told her not to do that it only worked for a few seconds. I tried really hard every time and that just didn't work for me.
Then I decided to ignore her. So when she starts pulling the leash or flipping out i just ignore her and walk on and after a minute she stops. She flips out very rarely now, she's improving!
Try with this method, maybe it'll work.