[Krishna's Mom]

Hoping for some good advice today. I feel pretty confident about the pros, but what are the cons of getting a second puppy? I am afraid of being overly enthusiastic and not really looking at the downside of a second puppy (if there is one).
Krishna is 6 months old and four pounds. I've had him for two months now and he's a very easy little boy. Very smart, easy to train, easy to teach. And very low maintenance as fas as Yorkie personality goes. He is not the alpha type and is very happy to have me and my hubby in charge. This is hubby's very first pet (ever) and he is 50+ years old by the way. I have thought about getting him a playmate in a year or so, but an opportunity has come my way and I am trying to think clearly before I pounce on it.
My breeder let me know she has a 6 month old female available who will have a very complementary personality to Krishna and will let him be "man of the house". She will also top out at 4 pounds max so she will weigh less than he does even though she is longer than he is.
Krishna likes to be near me all the time, but not necessarily held constantly and I think he would like to play more. I like to take him everywhere with me and realize that this would be less possible should I get another. Hubby and I also intend to travel a bit more when he retires in a year or so.
So...what's your best advice? Does he need a sister/playmate? Is there anything else I need to consider? It's so hard to figure out what would be best for Krishna.
Thanks so much for your help with such a big decision!!
Cheers,
Julie