How to know if I’m doing enough for my puppy?

I’m mainly asking this because sometimes he gets really crazy bitey and I can’t tell if it’s because he’s overtired or just being a puppy. Currently I take him on walks once a day (I’m trying to do two but the fireworks spook him) and let him play outside once a day as well. The bite inhibition doesn’t seem to be working he’s currently 4 months old. I’ve been doing absolutely everything, stopping playtime when he bites after three strikes, leaving the room for a bit, giving him a toy instead of my limbs. Sometimes it seems like he gets it for a minute and then he completely forgets and gets so much worse and jumps and bites me on walks. So I assume he’s tired and I end the walk. Is he biting me for a different reason? Please help he is my first dog and I really want to do the best for him.