I teach Chemistry A level. Don't feel bad, loads of students find it hard, especially in the first couple of months when they're finding their feet from GCSE.
But I have to say, most of the students do find their feet and it all starts to make sense.
Here are three top tips for you (and this is based on 16 years of teaching)
1. Make sure that you learn the definitions. They're in the text books (at least for the OCR specification) and they are really hammered in the exam. The best way to learn them is to write them out on individual cards and then test yourself until you know them.
2. Take each topic in turn (for example ionisation energy) and try to produce a mindmap from the textbook. That will at least tell you what you are meant to understand. Then go through each part and ask yourself whether you understand it and if you don't, get your teacher to help.
3. When you feel ready, get hold of past papers (they're on the exam websites) and look at the questions. Remember that often several topics are tested in the same question so you might not be able to do all of a question. And most importantly, really go through the markscheme carefully and see what the examiners were looking for.
Remember that unlike Biology (which I also teach), Chemistry does not lend itself to "how science works" type questions, so the answers are usually fairly straightforward, once you know it.
By the way, unless you have a really great teacher who gives you fantastic notes, then I'd stick to the textbook as your first port of call.
And remember, it does get easier. It's the first bit that's the hardest.