So am I bisexual?

I have been straight my whole life. Only got attracted to men. I mean I have looked at women and I find some women very beautiful, but never in a way I’d want to have sex with her. More like, she’s so beautiful or I wish I had legs, skin, boobs, ass etc. like her.

There is this guy I fell in love with. He flirts with me. He is very attentive and affectionate. He makes me laugh and I am always happy when I am around him. He knows I like him and he said he likes me too. A few weeks ago he told me he actually has a girlfriend. They have been together for 5 years. They have kind of an open relationship where they can flirt or date whoever they want to. But if they want to have sex, both of them will be involved. He asked me if I wanted to have sex with them. I didn’t answer him straight away because I didn’t know what to think.

I had been thinking and I really wanted to be with him, so after a few days I said yes. Last weekend his gf came to visit him and they invited me to his apartment. Well, we had sex. I am still not sure how I feel about it. While I didn’t have any kind of sexual attraction towards her, kissing her didn’t feel very different or when she went down on me. A lot of time I had my eyes closed and I was just enjoying the sensation. While I could tell the difference who was touching me when I had my eyes closed, I didn’t mind her touch. But I did not enjoy when the guy put my head between her legs and made me go down on her. I didn’t resist and did what I was supposed to do.

She told him she liked me and they would like to have sex with me again. I still don’t know how I feel about my experience. At times it was really hot and I enjoyed the attention when they were both focused on me. The part I didn’t like was when I had to perform oral sex on her. I didn’t hate it, it just wasn’t enjoyable for me. But he liked it so I would do it again. I still don’t think I am sexually attracted to her but I did have sex with her and I am going to again. So am I a bisexual?