I've just started questioning my gender, and have realized the more I think about being a gender fluid (between nonbinary and female) the more I feel that way. Am I forcing a gender on myself? How do I figure out my true gender?
To answer the question: Quite simply, no. A bit more in detail: you can choose which sides of yourself to express and live out. If you feel partially female but not entirely, demigirl can fit well for you, or genderfluid might also work if at different times you feel female and at other times something else, like neutral or androgynous. Apart from the knowing from an early age thing that I had, I was unsure of how I wanted to live my life, so I kind of put my hand on my heart and asked myself, who am I, and what do I want to do with my life? It's about honesty and authenticity brought to their extremes.
Thing is in some cases it can be that when you start to look into things you might start seeing traits of it in yourself and think you are that or try to fit yourself into the box of something you're not. It's like what you have a sore throat and search on Google and come out wanting to call an ambulance because it says you might have cancer. I went through something similar with an eating disorder when I was younger because I was susceptible and suggestible, researching and seeing that I had *some* symptoms made it even worse. I'd honestly suggest not going on any LGBT sites or researching for a couple days. See how you feel in everyday life, how you see your gender identity in the future, what you want from other people (change of name or pronouns) and just take it from there. Don't rush. Questioning can be a long process and this isn't always an easy black and white situation.
I think this is it exactly. You can't choose how you feel. You can choose how you express it (or don't express it). Just relax on trying to figure it out. There's no clock on deciding a gender identity. Do you feel a need to change pronouns with your closest friends/family right now? Does being referred to in a particular way bother you to a point where you're worried for your mental or physical safety? If the answer is no, then take your time! Like Aberrance said, you might want to take some time away from LGBT sites/resources and let your thoughts develop on their own.
You are the person you are, you'll still be that person no matter what life you were born into or what you do with it. But, words are not timeless things. Words come and go, words change. So you have 100% choice into what you call whatever it is you are. You're the only one who can decide if it's accurate and if it feels good. And if the word you pick changes the way you understand yourself and the things you notice about yourself, that's okay. You can't get stuck in a gender unless it ends up that it's the right gender for you. Similarly, you can't permanently stick yourself into a gender unless that's the right gender for you. Either it'll keep fitting, or you'll notice places where it's just not right, and you'll have more information about what it is you're really searching for.
