I wouldn’t necessarily be worried. Sexuality is something that is with us our whole lives, so it’s okay to discover new things. The fact that you liked kissing a girl may or may not say anything about your sexual orientation, depending on what it means to you personally. So just take some time to think about what certain romantic/sexual activities mean to you, what makes you attracted to a person and how you determine whether or not someone is relationship material. However, I would keep your boyfriend in mind. If you’re interested in further exploring activities with other girls, which is totally fine, but if your boyfriend wants an exclusive relationship you may want to consider talking to him about it.