Umm... This should be in a different forum...
Anyway, I find I never have time to check my exams and I have struggled with time - i.e. the Human Health and Disease paper in OCR biology on monday. That was because it was my weakest module in biology - I studied it at the beginning of the year, and assumed that I didn't need to go over absolutely everything.
What I think you're lacking may be revision; correct me if I'm wrong.
If you don't revise effectively enough, you will hesitate more when writing - even if you don't notice - you will pause for a second or two longer to think, but if you know the subject like the back of your hand you will find you can do it with plenty of time to spare because you know what to write immediately.
Try to stucture yourself... A minute a mark, a minute a mark. If you have a 3 mark question, try to spend 2 minutes on it. If you have a 10 mark question, spend 6 minutes on it etc. If you are confused on a question, move on, and our brains are amazing - while you are consciously working on the next few questions, your brain may be subconsciously working on the last, so you may understand it when you go back to it.
Just my 2p.