I have sat reading your post and trying to work out what to say. You are obviously unhappy with the situation and...Yes... at 14 you do tend to need more of your own 'space'.
Can you sit down with your parents and explain that you need to become more independent with your schoolwork and only ask for help when you cannot see the answer yourself or would like some constructive criticism.
'Back before' & 'bed' timings are always going to be a problem between parents & children. It was the same when I was a child. Can you work out some sort of compromise? Maybe one night a week (if you are not overloaded with homework) you could stay out til 7..... or an extended 'bed' time on alternate days.
You could also raise the issue by saying...
'Do you think it would be possible for me to stay out til 7 on Wednesdays'......or 'On Tuesdays and Thursdays could I stay up til 10.....if you think I am getting too tired then we could go back to 9.30'
Don't expect a decision straight away... it may take a couple of days.
Always remember that your parents are trying to raise you the best way they can....children don't come with an instruction manual
and teenagers do change so quickly it sometimes takes parents a while to realise that their son/daughter is on their way to becoming an adult.