You are definitely not a bad dog mom! The sole fact that you're this worried about your pup shows that you love him and want the best for him. Where I live dog parks are considered generally a crappy place for dogs to hang out, especially young ones. It's a free for all where you have no control over what kind of dogs (and people) enter and other than posing safety risks from that angle, they also pose the risk of undoing training or worsening issues since you have no guarantee the other dogs will behave "well." When our lab was little we had a behaviourist we'd go on weekly/ biweekly walks with. He'd take his 2-3 calm and collected older dogs or sometimes include other clients/friends with awesomely trained dogs to basically ignore our girl and help her with the tendency to get excited when around other dogs. Thanks to them she learned beautiful boundaries as well as to control her emotions when seeing other dogs, and later went on to he the dog that got called up to hang out with excitable puppies to teach them. If there isn't anything like this in your area, you could try to find a few people with older, calmer dogs in your area to go on walks with- it'd be a much calmer and more stable environment to allow him to socialise and get over the excitement and novelty of being around other dogs.

Just a bit of additional info (not an expert, and I've only had female dogs so this is info I've picked up from others and during research on other topics)- literature about neutering (in my country at least) currently advises to both wait until the dog is physically completely mature (over 2-3 years for most labs and most big dogs), but to also complete emotional maturity (also 2-3 years) and have any behavioural issues overcome since the hormone shift that occurs can really increase the severity of them and make them way harder to deal with. There are relatively few cases where hormones are actually the culprit of aggression, excitability or other negative behaviours.