You could use bookmarks on the last chapter you read then update it as you go?
There is a bookmark option here, I don’t tend to use that but I make notes on my reading section so I remember
You cannot keep on with the bookmarks each time. Nobody goes on with the bookmarks they could at least put the tittle of chapters that you've already read like in a more darker color so you'll know not to click on it
I use bookmarks if I didn't get through a complete chapter and I use the description (when you add the manga to your list) to write down the last complete chapter I read
Still I still think they should add something that would help everyone because what if you forget to bookmark it? Idk but as me I think they should fix that part since most of the webs have that feature when after you read something it has a hint that you've already read it or something.
reading in pages mode is very convenient when you bookmark cuz it bookmarks the specific page. however if you're on multipage mode, it just bookmarks chapt 1, page 1. bookmarking might be kinda annoying to you but it's the closest thing to keeping track of where you at. this site lacks a lot of things compared to other sites. just gotta live with it i guess.
I wish mangago would do something about the manga, I always forget where I leave the manga at and I'll have to start over or give up on it. It's quite frustrating when you think about it.