Look, I'm lately having too many problems with my sexual orientation (don't know if due to dissociative issues or not, I'd like to know if it is or what...because it's really odd). I'd ask my therapist for help, I cannot help you in regards to that, I neither know what it means that one of your alters is straight, but I don't think it matters. I know how puzzled you feel because I feel very puzzled and unable to express my feelings lately, but...if you are okay with being a lesbian and you are sure, and you love your partner, stick to it. Anyway, who am I to advice you, I analyze everything a lot and I would feel as puzzled as you.
Just hold on and keep there. Things will get better.

Maybe you had a very hard time accepting you were gay and an alter of you is straight because you couldn't accept you are gay? Don't worry. If your life fulfills you, probably you are going the right way. Don't give it too much thinking and do what makes you feel good. I would have to make a post about me, but for some reason finding the words is hard...my head goes fuzzy anytime I try to explain anything...