It sounds like you are doing the right thing then...consistency is key with the biting. Part of it is age too so just stick with it and every single time, if he play bites, yelp and look really hurt. Then stop play all together. He will get it!
Is there some puppy groups you can join? Or some dog socials? There is one in our area once a week, you can pay $10 and it is 2 hours at a fenced show ground where 2 trainers supervise, but all the dogs get to play. That is good if you want some help, training tips, or just general supervision.
Dog parks are hit and miss. Don't totally write them off...you just have to find the right ones. Some are places where owners just take their big rambunctious dogs with too much energy to burn off steam in a non structured way, and some are a lot more calm, where owners are having fun and everyone is engaged. I love the park we take Brooky to, but I scoped it out for a few days first (some I scoped out were too chaotic for me). Basically, after spending some time there, driving by at different hours, I now know what time to take her when all the dog walkers won't be there and the early morning rush is gone and the small dogs start arriving. If you are flexible during the day, you could just go for some drives and if the park looks good or empty, give it a try! I always stick with the rule that if I ever feel uncomfortable or some dogs want to play that are out of Brookies league, I just call her over with some chicken and we get on our way
I love the park because it gives us so much space to play and she can meet other dogs. I always ask the owner of a dog who is approaching (even if I have to yell from far away!) "is your dog okay?" just to make sure. You would be surprised that owners will answer honestly if they aren't good with small dogs or something. Or if Brooky gets scared by a big dog (even if it is being really nice) if she is scared I just ask the other owner "your dog is being very sweet to mine, but would you mind moving your dog a little bit away as mine is just scared." People always respond nicely.
Also, Brooklyn is 100% focused on me at the park. I always have chicken, a ball and we play (with some occasional dog play too). Best just to get a feel and do what you are comfortable with. The first few times I only went in when there was no one there!
Just so I could get comfortable myself.
Sounds like you are on the right track though!!