There is a certain type of lesbian who likes a certain type of heterosexual woman - one with shades of a '50s housewife, but with modern mores, and a little Marilyn Monroe thrown in. It might not be politically correct to say it, but many lesbians habitually crush on straight girls.
What it all comes down to, nonetheless, is who you're attracted to. Who do you want to go down on? Do you find male genitalia arousing or is it just when it's attached to someone you care for? Do women turn you on?
These aren't simple questions. Watch some porn and find out who you identify with - and who you're lusting after. While porn can serve as self-sex therapy and as a guide, you may only know if you prefer women through sexual intimacy with a woman or two. Take care, though, because it sounds as though what you seek is love and romance. It's not just men; seeking true love with one person is no easier among women than you've already experienced.
No matter what you uncover about yourself, in discovering your bisexuality, lesbianism, or even your heterosexuality, you may find the true holy grail of happiness: self-actualization. Now that is the path to personal bliss, single or otherwise.
As the Bard famously said, "To thine own self be true." Otherwise, we remain as strangers in a strange land, and there is no genuine happiness, no matter who you choose to keep you warm at night.