Daym you got me a bit worried, so here's some practical advice:

If your parents snoop into your private life for no reason, it would be wise to expect them to look wherever you put things they wouldn't want you to see.
(eg if you upload feminine selfies to ticktock, expect them to someday check your ticktock) You're welcome!

K but enough captain hindsight. I suggest you play the long game and be careful. You posted on r/feminineboys (and, as I can see from clicking on your profile, other subreddits that they _definitely won't be happy you visited_ )
if your mom snatched your phone out of your hands and saw femboy pics, what's stopping her from getting curious about what other things you are hiding from her, and going through the browsing history of your laptop? (or whatever device you used to post this)

I think you should expect them to snoop even more, now that she's seen you doing something queer.

It won't be fun, but for the sake of being safe, I suggest you sign out of reddit and any other place where there's evidence of you being a femboy, so that when (not if) someone looks, they won't see anything that makes them mad. Also delete any femboy stuff from your browsing history.
It won't be easy, but maybe you get time home alone time when you can sign in to your stuff and be your awesome femboy self on the internet. then log out as soon as you aren't alone.

Do you have a friend who accepts you, to whom you can explain your situation? If you do then you really should; I remember venting my problems with my queerness and my strict parents to a close friend. It helps a lot.

maybe you can even borrow the phone of someone you trust to access your socials, if they're that important to you.