Biting a real problem with 18 week old

[Finley_23]

Hi, I am new to the forum and wondered, what am i doing wrong. I have looked at members whoes puppies are 12 weeks old, but mine is now 18 weeks old.
He is a lovely boy, very social and quiet obedient for a puppy of that age and we love him to bits, the only issue we have is biting.
Finley has started, mainly at me, nipping me on the legs back and front and biting my hands and fingers, which is not a puppy nip, it hurts when he gets hold of you and can draw blood, he has also brusied me quiet a bit.
We have recently had a challenge getting him into our truck, which is high up so we have to lift him in. He is getting very big and heavy and think hes now taking a dislike to us lifting him in as he growls a bit.
I am very worried that he is now getting out of control a bit and need to stop this before it gets out of hand.
I have now spoken to a dog behaviorist who says it sounds as though he is being disrespectable to us and he needs some behaviour training at a boot camp. I dont want to let him away from us and is very upsetting. We have tried all the exclusions and nothing seems to be working, is there any advice please

[Dawnspell]

Hi I've split your post to make a new one.

You havent said what size I'm presuming not a mini if hes getting heavy? Growling is him trying to communicate hes not happy, thats his warning before a nip or a bite to keep ignoring it wouldnt be good. Hes not being disrespectful he trying to tell you hes not comfortable with the situation.

The biting of legs in puppies is normally due to a combination of over arousal, being tired a puppy of that age should be sleeping at least 20 hours a day, or thinking something unpleasant is going to happen. Its normally if you are moving quickly too as that adds excitement. if you could give some examples of when the biting happens.

With regards to the truck could you use a step or a truck so he can climb in himself until he can jump in ? If hes not a mini youre probably not going to be picking him up anyway, bit tricky what to suggest with not knowing the eventual size.