I think as long as she seems happy, I would leave well enough alone. If she doesn't like other dogs, then I wouldn't bring another in to be her "buddy". I think that's asking for trouble as was said by someone else.
I think as long as she seems happy, gets the love and attention she craves, then all is fine. Like they say...don't fix what ain't broke.
But, I know what you mean by thinking she is lonely because Suzy is gone....