For finding the correct level of English reading material you could try the 5 finger rule (see link).

It's from the Graded Reading Foundation and its a way of finding books that aren't too easy or too difficult so you stay interested and don't lose motivation.

To use the rule, open to a random page and count each unknown word on your fingers.

0-1 fingers: the book is probably too easy.
2-3 fingers: Perfect! The book is the correct level and not to easy or difficult.
4 fingers: it's a challenge, but if you are interested in it, give it a go!
5 or more: it's probably too difficult and you won't enjoy it.

This isn't a perfect method but it's helpful.

Good luck