Only you can know if you're straight, bicurious, etc. One thing I'd like to mention is, straight people who've never been in relationships never get asked "then how do you know you're straight?". You just know. Just because you've never had a relationship with a woman doesn't mean you're not bicurious (or bisexual). You might be, you might not be. If you know that you for sure like guys, what might help you figure things out is start paying attention to if you think about women the same way you think about men. Do you like them in a similar way? Can you imagine yourself dating women? Ask yourself things like that, that's what helped me sort out my feelings, I hope it helps you too