As long as you keep using the language, read different kinds of materials and look up the parts of the grammar you're not good with, you should be able to improve. If you have an English textbook (which you use/d in school), practice with it and it'll probably bear fruit. There are also lots of videos on Youtube explaining different aspects of it so maybe you can give those a try too.
As long as you've got the will to improve it should all go well.
Cringing at your skills is part of the process hahah