I am very much in the same position. It's crazy how much I can relate, and it makes me sad thinking about how many other people are also going through the same thing. 'Snapchat filters that blur my skin remind me of how much better I would look if only I had poreless skin and crazy long lashes' really hit home. It's got to the point where I cringe looking at myself without a filter.
The past year or so, I made an effort to unfollow people who very obviously edit their photos. You describe liking yourself more with Snapchat filters. Well, the majority of people on Instagram are also very heavily filtered, too! Don't compare unfiltered you to photoshopped models. Now I only follow those who I can see keep in their pores, texture, and other things we often consider imperfections. Seeing that on the regular, as opposed to the typical flawless Instagram models, has helped a lot, as well as avoiding the explore page! I've actually grown to love my skin texture because it's natural and part of being human. I look at others and find their mismatched freckles, or little scar, or patches of texture, uniquely adorable, and actually kind of endearing.
I'm not sure if you're into the beauty Youtube scene, but I have always loved makeup tutorials, and most of the popular gurus are sat under heavy studio lights with blurring filters. So I've made an effort to only watch Youtubers who aren't afraid to show their real skin. ItsLikelyMakeup, Samantha Ravndahl and Shelbey Wilson are awesome for this. I've also tried to just generally limit the amount of time I spend watching beauty tutorials.
I would also emphasise that we are our own biggest critics. Nobody judges us as harshly as we judge ourselves. The tiny fine line on my forehead that I curse every time I see a mirror? Probably nobody notices it, and even if they do, they probably don't care. A big game-changer for me was when I saw my friend, who I always idolised for her beautiful skin, up-close. No shade, but her skin wasn’t as flawless as I had always thought! I realised I always look at and critique myself super close to a mirror, but nobody is getting up in my business like I do, and so my skin probably looks fine to them!
Another thing I like to remind myself of, is that online, people are literally paid for looking good. It's their job to look totally flawless at all times. It isn't mine. Which has become a really freeing and comforting thought.
I wish I could offer more advice. The most important thing is to limit your exposure to these perfect Instagram models, and stop being so harsh on yourself. Easier said that done, I'm very aware, but worth at least working towards. All the best!