Things to look for are sturdy builds. Avoid extremely tiny dogs with spindly legs, long-backed dogs with very short legs, or anything with a shortened face that will have a difficult time breathing while playing.
Think about what sort of personality appeals to you. Do you want a feisty terrier type? A smoochy lap dog? A big dog in a little body? Ultimately this will be your dog, and you want to pick a friend who will do well with you when you have moved away from your family.
I am going to step on a lot of toes here, but I wouldn't get a King Charles Cavalier Spaniel because the breed is riddled with health problems. They are lovely, sweet, nice, amazing dogs, but when dogs die terrible deaths because their skulls are too small for their brains, or when fluid builds up and squishes the brain out of the skull and pinches the spinal column like it does with Syringomyelia
and a huge litany of other health-related issues that you can read about at Cavalier King Charles Spaniel - Health & Genetic Diseases
. For many of these conditions the first and only sign is pain, which a dog can live with for years before the owners realise what's going on, and in many cases the prognosis is very poor. If you are not in a position to be able to pay for these sort of medical expenses, it's not fair for your parents to foot the bill should something arise.
I think something like a cockapoo or a bichon could be right up your alley. Snuggly and active without being too hyper or fragile. Look for a dog that will end up closer to 20lbs than 10lbs. You will still get a lapdog, but the sturdiness will pay off in less chance for broken bones.
Your best bet is to do as much research as you can. Ask questions here; you'll find lots of very helpful people. Good luck!