Hun, you are definitely not alone!
Unfortunately, it seems we are
all our own worst critic - whether trans or not. I think it's safe to say that pretty much everybody - or at least the vast majority of us - have a negative inner voice that seems bent on bringing us down and making us miserable. And being trans, I think, brings on a lot of extra pressure of trying to "fit in" to the correct gender we were sadly not born into.
When I first came out, I was hit with a lot of insecurity about my masculinity - or rather lack there of. I was informed by my mother and brother that in order to be a "real man" I had to change all these aspects about myself so that I could fit into some cookie-cutter stereotype of what a man is supposed to be. It's ridiculous, unfair and unrealistic. Nobody, not even cis people, fit into the projected "standard" of what a male or female is supposed to be. Yet I found myself being pressured to do things that not even my cis-male friends and family felt the need to do in order to be a accepted as a man... like watch football or... pick fights with people...

lol. It's really just a bunch of nonsensical hallabaloo perpetuated by unrealistic societal standards that people like to blow out their butts. But if you are able to step back and look at the reality that these are ideals that
nobody can live up to, not even cis people, you start to realize how incredibly absurd and silly it all is and maybe even have a good laugh about it.
But I know it's easier said than done. Changing your inner voice is a process and it takes some work to break the habit. I certainly still struggle with it, and I'm not sure if there will ever be a time that I don't, but it has gotten much better than it used to be since I have started working to consciously change my inner thoughts. Often times I feel a bit like Pinocchio, wanting so bad to be a "real boy" but being unable to physically embody that. It seems like every time I try to assert myself as a male I can feel my nose growing a bit longer... haha. Hopefully when I start T that will start to go away. But it is hard to kick something out of your brain that you've been told your whole life. Still, I have found that the less I care about the images other people try project upon me of what I should be, the easier it is to accept and love myself for who I am, even the things about myself I'm not too crazy about.
So! You're a girl who plays video games? So what! There's nothing wrong with that, in fact I think it's awesome! Video games are fun as hell and there's no reason guys should get them all to themselves just because the general public deems it as a "guy thing". Screw that. Hey, my cousin is the girliest person I know, but catch her on Halo and she'll pwn every single one of her male counterparts, haha.

On the contrary, I am not even remotely competitive and don't like first person shooters. I'd much rather zone into some cutsie, adorable game like Farmville or Viva Pinata, hahaha.

You are who you are, you like what you like. There is no shame in it. Just because we are told we "should" be this way or that way doesn't mean it's right. We are human, and we are all wonderfully different and unique. We are not wrong in being who we are, society is wrong for trying to tell us who we are. Being true to yourself is probably one of the greatest gifts you can give to yourself. And the more you allow yourself to accept you for you, the happier you will be. You are perfect just the way you are. I know you probably don't feel that way right now, but I truly hope that someday we will all be able to feel that in our hearts to be the truth.

One last thing before I stop my rambling... haha. My therapist recently recommended to me a great video about self-compassion that I found rather profound. I truly think it's been helping me to turn that negative, self-critical inner voice into something more positive, so perhaps it will help you as well.