The first thing to point about is that plenty of people have fantasies that they have no intention of putting into practice. Having bisexual or gay fantasies is a classic example of that, and does not mean that you are bisexual or gay. However, chances are that the way that porn works is absolutely a driving factor here. Porn is not real, and in fact it has virtually no bearing on sex in real life at all. That starts with the actors, who are just that; actors. They are performing in a scene that they are doing because they are paid money for it. So many aspects of a porn scene are completely artificial. It is the exact opposite of how people have sex in real life.
That's the actors, but it is also an artificial experience for the viewer. Real sex involves people who, first and foremost, get into the mindset of wanting to have it. That doesn't happen every time one person wants to have sex within a relationship. When it does happen, the enjoyment of real sex comes with experiencing it with that other person. That is an organic experience. Sometimes it will be better than others. But the extent to which you and the other person enjoy the sex comes from how well you're interacting with each other. That can be variable, but it is a very different type of experience to watching porn. There's no issue of consent in porn; the videos are always available, and the people in them always willing to do what you want. The outcome is certain, and it takes no effort to go get to it. When you're having sex with another person, there will be times when everything clicks and you both have an amazing time capped off with both having great orgasms. The fact that that doesn't always happen means that when it does, the feeling is absolutely fantastic. It is significantly better than anything porn can give you, and in fact porn works in a very different way. Because the outcome is certain and takes no effort, the 'progression' is that you will end up watching more and more extreme content in order to feel more of a thrill. But it gives diminishing returns. Much like taking drugs or alcohol regularly, the effect lessens so you end up taking more to get the same buzz. And that can be really detrimental. In the case of porn it will distort your view of how real sex should be, and it will stop you from enjoying actual sex with actual people because psychologically you won't be able to properly engage with an actual person in an actual sexual encounter.
The upshot of all of that is that, no, you're not bi or gay just because you watch bi or gay porn. But you should absolutely acknowledge how porn is likely distorting your own view of sex, and indeed your own view of your own pleasure. I'd seriously try to cut back on watching porn, because it is going to cause problems for you if you eventually get into a relationship with a woman, but are only used to getting sexual pleasure from watching sexual situations that could never happen in real life.