Help to train 2 years old German shepherd

Hello everyone. I'm 18 years old owner of German shepherd since she was 2 months old.Since day one I'm trying to teach her to not to push on a leash but it doesn't work for almost 2 years she constantly push. I live in Croatia in area without dog trainers. My main objective is to make her stop pulling on a leash for now. Also she is becoming now w little agressive towards smaller dogs. Can anyone help me? Btw i tried videos on YouTube, but it only works with food... She knows how to heel also, but as I said it works only with food. Any help would be great 😃👍