I just feel so out of depth 
This will be really long....
I bought a border collie puppy years ago, I was never able to successfully teach her to walk nicely on a lead and a combination of her breed (which I now know often are not sociable with other dogs) and some out of control dogs behaving aggressively to her meant that she matured into a fairly dog intolerant adult, not ‘dangerous’ but grumpy, would growl at most dogs if they approached her.
But, she still wanted to meet other dogs and sometimes was fine and had a few dog friends.
Apart from those two issues she was and is a fantastic dog.
I wanted another but experiencing aggression from other dogs and her and other dog’s owners and being unable to do much to protect her due to her size seriously knocked my confidence and I wanted a breed less likely to be dog reactive and super small so I could move it easily if necessary.
So I bought a chihuahua puppy.
He is lovely but he could not be more different to my collie and frankly, I honestly don’t know what to do to manage him properly and feel like I am failing.
My collie was so outgoing and confident, basic things like putting a collar on and going for a walk were no issue whatsoever.
The chihuahua is nervous.
He was so scared to wear his collar (to the point of yelping when you tried to clip it) that I threw it away and opted for a harness.
While the harness is easier to get on he is scared of that too.
He is scared of the leash clipped on and off aswell.
I often have to carry him for the first few minutes of a walk as he’s scared then he relaxes and seems to thoroughly enjoy walking.
As a puppy my collie adored attention from strangers, being so small and cute everyone wants to stroke the chihuahua but again, he is scared.
He is getting good at walking past people and he can usually sit quietly and take treats with people walking around but he isn’t comfortable at all with strangers actually approaching him.
When it comes to training, unsurprisingly, my collie was super keen to work and please people and therefore easy to train.
The chihuahua is very clever but he only wants to learn if he is hungry and will only do as I ask if hungry.
There is pretty much zero desire in him to please people and work.
My collie likes to play with you, fetch or tug or finding items and so again, training is easy because if she isn’t hungry enough for a treat a toy can be substituted.
This little guy wants to play alone.
He wants to run around and rag his toys.
No desire to play with people at all.
The little puppy isn’t particularly affectionate either, unless he’s tired, then he wants to snuggle in your lap, but the rest of time he wants to pester my other dog, play with his toys, eat and any attempts to stroke up generally result in (non aggressive, puppy) biting.
He’ll run to you happily to say hello too but that’s about it.
He won’t walk in the rain, toilet training is going appallingly.
I just feel really out of depth.
I have no clue how to train and motivate this little dog and have visions of him maturing entirely untrained and completely disobedient.