The logic is there, for waiting, but I cannot in good faith tell you to wait until the pup is older, because that would make me a hypocrite
We got Kito in August, Abbey in November, Riley in March, and Jada in September--that's 4 in just over a year!!!!!!
As far as a good companion goes, you'll have to judge that for yourself, when you see how your pup plays with others. If you think she is a bit rough, then you may not want to get a toy breed, but you never know how they will play together.
Research some breeds that are around the same size as her--providing you have enough space for two dogs of that size--and then see what comes up!
Personally, my little labbie loves his rottie sister--they play for hours and hours!!!!!!
Your girl is beautiful!!!!!!!!
Emily, Kito, Abbey, Riley, and Jada