You are not alone!!!
I have a ten month old cocker spaniel and it has been such hard work, but incredibly rewarding, all in equal measures.
Its hard to describe just how much I love him and how I miss him if he is not under my feet! But, the first few weeks were hell, but he improved slowly and steadily, and looking back all the hiccups / issues were actually my fault!
I am a supporter of crates, and would recommend them for all puppies, LizzardDog loves his, both at home and in the car - he feels safe, comfy and secure.
Looking back, the best two pieces of advice I received were - Socialisation and Training Classes. I met with my trainer when he was 8 weeks old and she gave me a check list, a sort of doggy challenge to introduce him to as many different situations, dogs, people, environments as possible - and I now have a very chilled dog who is phased by (practically) nothing.
We still do our weekly puppy classes, and I intend to continue well into his adulthood. A good trainer will ensure the classes train the humans as much as, if not more than the dogs! I have learnt so much about doggy behaviour, and how they learn. I genuinely believe this has allowed me to make a happy home environment for my pup and to set his boundaries in a firm yet fair way.
It does get better, and before long those nightmare first few weeks will vanish as a distant memory and you will love your pup more than you can ever imagine. Mine certainly isn't perfect, we still find chewed shoes and clothes, he will still steal food given the chance, he will still run and hide in the undergrowth if the mood takes him!!