Quite often, a content, well fed, comfortable pup doesn't cry. You may hear some mewing sounds (almost like a kitten) but if all needs are being met, there won't be crying. You mentioned the two pups you lost cried - that usually means something wasn't right - hungry, cold, too warm, etc. Sounds like things are right for this pup.
As far as a singleton pup goes, take a peek at this link for suggestions on socializing a singleton - they tend to have slightly different needs since they don't get the tactile and competion experiences as a normal sized litter.
The Singleton Puppy | Susan Garrett's Dog Training Blog
Best wishes with your pup!