I don’t think it’d bad for you not to include any LGBT+ characters in your story, especially since your reason is better than adding them and portraying it badly. However, as others have said, research could easily help this. Even easier than that, there’s most likely many threads on it on these forums that you can read.
Plus, LGBT+ people are not so different to everyone else so there’s no one way to be LGBT+ because it encompasses many different people and identities. Ultimately, it’s your choice though (: