My fear and anxiety

My beautiful girl is a rescue (I've posted before about it). Now that the weather is getting better and we having beautiful days. We have been trying to go to the dog park. Just so she can be off leash and run and play until her heart is full.

Buuuuuutttttttt.....

I'm having the hardest time letting her stay off leash and play. She is a big dog who sounds mean as hell lol (I truly don't believe she has a mean bone in her body) but I'm terrified that something is going to happen whether it be to her or another dog.

We have gone 3 times now one time there was no other dogs, so she was able to run and play catch with no issue. The first time she did great with 2 huskies, then a younger golden retriever came and it was OK but the pup kept getting in her face and at first it seemed like Raven was trying to correct him but then she snapped at him and I had to grab her. The owner of the pup looked at me like I shouldn't never have brought her there.. So we left... I was a bit scared because I've never seen her do that. My brother told it was normal she had tried to correct the behavior and the pup didn't listen.

So today we tried again, I don't know if it was because of me and my fear an anxiety that she seemed on edge or if it was actually her. It's like she wanted to play but at the same time was extremely stand offish which made me even more nervous to let her off her leash. I was trying to walk her around the park to calm her down but one kept coming up she got agitated and they kind of went at each other. He got her to the ground (I still had her leash on) so I was able to pull her away while his owner grabbed him and corrected him but she was terrified of him the rest of the time and would growl when he came near.

So outside of my rambling, I guess I'm asking for advice about what I am doing wrong and how I can fix it for her? I know she is ok with others because the lady that originally recused her had 2 other dogs that she was great with. So is it me and I'm making it harder for her? I'm just so lost atm I guess....