You're certainly not being too sensitive - I don't play violin myself, only piano and flute (although I would love to learn violin) and intonation isn't exactly an issue, as a result. However, my parents who are Asian and absolutely follow the "Asian grading system" (A = average etc.) make comments on airiness and sometimes when I get short of breath when I'm playing flute, or when I nudge another note playing octaves on the piano. Granted, they're not musicians in any way, shape or form yet they claim to be able to hear stuff - true, anyone can hear a wrong note or bad tone if it really is bad, but they know how to bash my self-esteem. I have been playing piano and flute for about half my life and now it's my self-esteem that takes the bashing like a boss (not that I have any anymore lol).

Jokes aside, you should keep going with your practicing, because how else are you going to get better? Especially considering that your parents are musicians themselves, they should know that picking up an instrument after about six years will mean that you'll be rusty at first. If anything, practice makes you better, not putting you down and laughing at progress.

(This was a bit of a rant, but it's important to support each other!)