Can I be polyamorous if I'm straight?

I found out that I’m into polyamorous relationships. I only opened up to one person who is an acquaintance plus I have a crush on and thankfully he took it well but I sort of feel excluded since I don’t considered myself bisexual nor lesbian. Is it okay being interested in one gender while being poly?

Who is making you feel excluded? Those people are wrong and being obnoxious. Being bisexual or lesbian is about who you are attracted to; being polyamorous is about the type of relationship you want to be in. They are completely separate and can be mixed and matched in whatever combination is true for each individual. There are monogamous bisexuals, polyamorous lesbians, monogamous heterosexuals, polyamorous heterosexuals, you name it. Relax - you are you, and if you're polyamorous, then you're polyamorous.