My DD Anna wouldn't hold toys either. I don't think she had the fine motor control required to do so. By age two she would hold onto toys, but until then she could hang on for seconds at best. Compounding the problem was that she has a lot of sensory issues so she didn't like the feel of lots of different items. Anna is also quite social, but wasn't interested in toys...at age 4 she's still not really much of a player, unless of course it is something with music and lights in which case she'll play non-stop (hit the buttons over and over and over) and she's been like that for as long as she could actually press down the buttons.
As far as being around typical kids, it can be tough. Sometimes I make a point of saying right away that she is delayed, and other times I don't say anything unless I'm asked or a situation arises where the explanation is needed.