I totally totally relate OP. You're not alone.
People call me "pretty" and I guess I could be considered "pretty" but I'm not classically "good looking" and very much un-photogenic. If you caught me at the right angle I'd look "pretty" if you caught me at the wrong angle I'd look quite grim.
The camera doesn't like me , my features just aren't "strong" (chinny, long face, no eyebrows - tattooed on) and fatty cheeks and disappearing eyes when I smile. I look better if I don't smile ! My features just aren't fit for a camera. I can become very low on myself when looking at photographs if taken from a poor angle or they've caught me wrong. I am very self critical though. Some days (if my hair goes right and make up sits well, I feel pretty) if not, I feel really unattractive.
I totally understand. Some "plain" people (like Katie Holmes) have good, strong features and are photogenic and considered "attractive" even though they're not "pretty" as such , and I think that's easier to work with personally!
I think "beauty" has changed. "Pretty" was what was desired in the 20s, 30s, 40, 50s etc. I'd probably have liked how I look more if I was in that era. Now, it's all about symmetry, and angles and bone structure and long, straight figures. Even if you're "plain" you're considered "better looking" and more desirable than someone who is "pretty".
I've ran on a bit. But yes solidarity, I get it.
I've just decided I'm not even going down the "tweeks" route. I'll just start picking on the next feature that I'm unhappy with and it'll become an obsession. My DH thinks I'm gorgeous and my children love me and at least I am "pretty" by a few peoples standards, some people have a lot harder luck, looks wise. Sorry you feel the way you do x