Okay so firstly, do you want to transition? If you do you are likely not going to be staying at that school. Most schools like that are either religious in nature or rather stuck up, so even being fluid could make them decide that you aren't right for their school. Next, if your parents don't understand, it is up to you to educate them on what it means. Of course since you are telling them something untrue you should plan to be doing this more than once when you eventually come out as trans and further confuse them. Strictly speaking someone who is fluid will generally be called by the pronouns that are attached to their sex because from one moment to the next there is no telling which side they are on. The only option is they or them, but getting someone to do this is not easy nor the norm. Being at that school means you will be stuck conforming to their dress code, which also means you wont be able to do somethings that would allow you to be more comfortable. So you are going to have to decide on if you can wait until you are done with school to address this (letting puberty do its thing in the mean time) or if you want to deal with it now which means likely changing schools. You will also need to educate your parents and SHOW them you are serious. If you are saying to them hey sometimes I feel more male than female (which is what you did) and you are always wearing dresses, its hard for them to believe what you said to them. You are going to have to show them, again though, you also told them one thing that is untrue and so you are going to have to come out to them all over again at a later date. I recommend that you straighten that out and then educate them on it and show them as best you can (within the confines of the school stuff or including changing schools) so that you can have an easier time in the long run. Your parents are going to assume based on your age that this is a phase, because it is new to them. You have felt this way for a long time and never exposed it to them. So from their perspective this is just something new. You have to make them understand. Sorry if this isn't very helpful, but you are in a bit of a pickle with the school thing and all. You have two mutually exclusive elements and you're going to have to choose one.

Thank you so so much WyndWytch. I really appreciate your support. I mean its kinda obvious that that's what I need to do but I really needed someone to talk to and your advice made so much sense. And yes I definitely want to transition from female to male. I hope they understand and are fully supportive of me. I've done some pretty stupid things in the past and I just hope they don't think that I'm just going through a phase or making it up for attention. I'm getting ready for a major secondary school exam (GCSEs) and my school is a good school for getting high grades so I think i should wait a bit longer till that's over and tell my parents then and move school. Thank you again for all your fantastic advice and wish me luck on everything.

Absolutely good luck on the tests and all, I am sure you will do well. So with your parents don't be worried if they react a bit adversely at first. While you've known a long time it will be all new to them and there are stages of grief basically that they will go through. It will take time but long as you are showing them they should come around. if your parents handled fluid okay they seem like the type that will love you regardless. On the plus side, while there are some things that will never be changed once puberty sets in, going female to male is a but easier in society. You will always have wider hips than most men (not I said most not all) but your voice will drop on hormones, you will grow facial hair, muscle mass and all that. You will have to contend with mastectomy and all, but the change over all is a lot more effective. Also you will be able to wear what you want and have your hair how you want. Women wearing mens clothing isn't quite as attention drawing as a man wearing womens (the perception of the standard onlooker) so you will be able to weave in and out of public pretty easy. I am sure you will do fine in all aspect :D Good luck with the tests and all