16 week golden – is he badly trained or just a teenager!? help!!

hi! long one here…

so we have a 16 week old golden retriever. he hasn’t been an easy puppy so far, but between 8-12 weeks he responded really well to training; he picked up sit, down, up, middle, and heel training was going really well too! he also (after lots of work!) is fully crate trained and settles fine in there, sleeps through the night etc.

BUT

he has me tearing my hair out the last few weeks. his food drive has plummeted, so i’m finding it near on impossible to keep up with his training and it’s resulted in lots of unwanted behaviours…

– he is truly terrible at walks. even though i was training heel very early on, he will not respond to treats at all when we’re outside and just constantly pulls on the lead / jumps everywhere. i think the issue is that he has zero engagement with me. we’ve really struggled with name training as he just doesn’t respond to it at all despite daily training with lots of high value treats.

– i feel like i get no engagement from him at all most of the time. he doesn’t respond to his name or come to me when i call, even if i have the best treats. the only time he seems to be engaged with me is when i have him in my lap feeding him a frozen carrot or scratching his belly 🥺

– he gets overstimulated very easily and will start biting / nipping non stop. i know this is somewhat normal for a pup but it just seems to be all the time! he is getting enough sleep (18 hours on a good day) so it’s not always down to overtiredness

– he won’t ever let me put his harness or collar on without going nuts at my hands and biting and growling

– he doesn’t ever settle outside the crate/pen. we use kongs, long chews etc but whenever we try to chill with him he just gets too excited and wants to bite / chew everything.

any advice would be so helpful. i’m really struggling with the puppy blues this week, i love him to bits but i find i’m mostly just frustrated with him at the moment 🙁

is this all just normal puppy behaviour or are there things i could do to help?