Sorry to hear your grandmother passed away
I had a rough childhood that led me to socially isolate myself from others, including my own family. I also don't trust anyone either, but I think that lack of trust stems from my negative childhood experiences. Not sure about your lack of trust.
I do like being around people and talking to them, but I usually avoid those social situations because my social anxiety gets in the way. I just don't want to relive my past experiences, which is why my instinct is to shy away.
When I actually do talk to people (which is very, very rare), I try to come across as upbeat. I like to hide my true feelings because I don't want those feelings to become a part of the social conversation. I don't want to be a buzzkill.