Am I still bisexual if I'm attracted to the opposite sex 90% of the time?

yes!! bisexuality is super fluid, and it doesn't have to be a 50-50 split at all! you can be 99% attracted to one sex and 1% attracted to the other and you're still bi and you're still valid! and those percentages can change at any time, so it's totally ok if you find yourself attracted more to one gender one day and another gender another day! it's completely normal and your experience is completely valid :)

Sure! You don't have to feel a 50-50 attraction, you can have a preference for one gender, even a very strong one, and still be bisexual. Every percentage combination is possible, if you're not 100% attracted to one gender you are bi. 90%-10% is bi!

Bisexuality exists upon a spectrum - not everyone that is bisexual is equally attracted to the same and opposite sex. But that doesn't make your bisexuality any less valid. You could be attracted to the opposite sex 90% of the time, or 10% of the time, and you are still bisexual. As you go through life, these percentages will change as well. You may try on different labels, and ways to describe yourself, but you are still you and still valid. Your identity is something that is important for you, and you alone. As long as you are comfortable and happy, you are valid.