I have a male yorkie (neutered, 3yrs old, approx. 11lbs) and I have a female maltese (spayed, 1yr old, approx 4 lbs), and they get along beautifully!! They love each other
My maltese is more rambunctious than my yorkie. She's a wild girl who loves to play but also knows how to cuddle.
I also have allergies, but I'm not allergic to my yorkie or maltese. Whatever you do, make sure that you find a reputable breeder...