I thought I was bisexual before but recently I’ve been attracted to more boys than girls, am I still bi or was it really just a phase?

As long as you're attracted to more than one gender, even if you have a preference, you are bisexual. It doesn't have to be 50-50, it could be even 99-1, but as long as you're into more than one gender to any degree you're still bi! And it's ok if you realize you have a preference, what you experienced before was not a phase, you are simply learning to understand your own bisexuality better.

Bisexuality isn’t a 50/50 split. Most people who are attracted to more than one gender have a preference towards one gender or another. If you are still sexually attracted to girls, then you are still bisexual, but you have a preference towards boys. If you are not still sexually attracted to girls, then you would be either homosexual(if you are a boy) or heterosexual(if you are a girl) depending on your gender (unless it’s nonbinary, in which case you’d be androsexual, or attracted to male presentation). I hope this was somewhat helpful to you, and you are valid no matter what!