What breed of dog is fitting for me and my lifestyle?

I would look at a local rescue that fosters their dogs, as that will give you more insight into the personality and energy level of the dogs. The older the dog is, the more of its personality and energy level you will know - puppies can surprise you, while a young adult dog (or even older puppy) will have more established personality and energy levels. Please keep in mind that even little dogs that can be held are still dogs, and still need exercise and structure. Depending on what you mean by "treat my baby like a princess/prince" (you could mean the best of food, beds, etc., or you could mean holding them all the time), you are likely to run into problems if you spoil any size dog with constant attention. Further, you may have trouble adopting (or even buying) a dog if you come across as wanting to baby them instead of treat them as dogs. Also keep in mind that more and more places are dog friendly, so traveling with a medium or large dog is now easier. Dogs (generally speaking) require more time than space, so if you are up to providing adequate exercise where you live now and where you will move to, a medium (or even large) dog may also be an option, although considering your boyfriend's dog it may be wise to choose a smaller dog. I have a rescue dog myself, and I think that rescued dogs are aware and grateful for the second chance. I would also be clear with the rescue group that this is your first dog, as many rescues and shelters have systems where they classify dogs as being "easier" (for first time dog owners) and "more difficult" (for people who have experience dealing with problems). Don't be shy about sharing what you have here with a rescue group - the right group will be happy to work with you. I wish you the best of luck in finding the right dog for you.