Sparkly – I don’t think Shopping613 meant to insult you. I think that she seriously thought you were a teenager. I believe she also referred to herself as a teenager, so she clearly did not think it was a negative statement.
If you feel insulted by something someone says, you should let them know instead of coming up with ways to insult them back. You might find out that you totally misunderstood them and they had no idea that you felt hurt by what they said.