How to come out if I'm not sure?

Something like "I'm not straight, I definitely lean more toward women but can't quite put an exact label on it" might cover you. If your parents are supportive they'll probably ask a lot of questions but ultimately respond well

 

A lot of people wait to come out until they find a label that suits them, exactly for this reason: it can be a little harder if you’re not sure. However, that absolutely doesn’t mean you can’t come out earlier. Maybe, instead of coming out as bi or gay, you could just say that you’re attracted to women - then if someone asks about men, you could say what you said here, that you first thought you were bi and now think you might be gay but aren’t sure, and that it might change. If you’re not super sure yet people might be a little more likely to doubt you in the beginning, but if you want to be open about this you definitely should. Have you thought about coming out to just your parents for the time being? It would allow you to step outside of that isolation, without having to face the potential judgement from your extended family until you’re a little more sure (being sure makes it a lot easier to defend yourself so you’ll be able to respond to anything they have to say a little better). Just something to maybe consider!

Most people who come out have at some point lied about their sexuality - that’s the whole thing about being closeted in a heterosexual society. In all honesty, even if you hadn’t lied, people would still have made assumptions and coming out would still lead to “but i thought you were straight?” comments. don’t worry too much about having lied - most lgbt people have done so and it s not like a malicious lie: you were just trying to protect yourself from being outed at a point you weren’t ready.

 

You might consider waiting since you're not sure, but if you feel like you need to come out you could consider coming out as "not straight but not sure if you're gay or bi". This will at least let them know you're not straight and allow a discussion like you said and perhaps you can all figure it out together.

 

I'm gonna agree with the rest of folks here, "I'm not straight" seems like a perfectly appropriate and valid statement. If you're close with your parents (I'm assuming you are, based on the post), I think, it's ok to go with the "I'm not completely sure" as well. You don't have to make up your mind right away and shout it out for the whole world to hear. With close people sharing the doubt might be just as important.