Ok...now I see - Heidi is your human fiance lol - I thought she was another pet....sorry !!
and the way I see it is Yorkies are high maintence both emotionally and physically - maybe you don't have the time to offer your new yorkie what he needs and if you feel in the long run it's not going to work out then I'd consider a new home.....as far as the bonding thing - I wouldn't worry too much as you've only had the dog a short time. Someone just said your yorkie just had his whole life changed and it's true - it does take them time to adjust.
The thing that catches my attention is how little you guys are home....they get very lonely being left alone....but having 2 doesn't take away from the attention you can give one....it actually gives the dog someone to hang out with - my girls are attached at the hip and would be so miserable if not together all the time but as you said - you aren't really home that much so IF I were to offer advise I'd say not to get another just for that reason.