Yes, as Gayleggg says, antidepressants may cause or contribute to flat affect. Your history and shyness may certainly also play into what you are experiencing.
Have you looked into shyness/self-esteem/social phobia resources?
PsychCentral: Self-Esteem & Shyness
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My dog
mastered the "fetch" command. He would communicate he wanted something, and I would fetch it.