When?

Soooo I am obviously looking for some advice on how to come out. I've already told some of my close friends that I knew in high school (I'm in college now), but besides that not many people know (general friends, classmates, roommates, sorority friends).
Okay, so I was raised Catholic and that was a big part of my life for a long time. Lately I've kinda rejected Catholicism and still trying to accept God, but definitely struggling. That said, last year I joined this christian sorority at my college, so my 3 roommates and a few close friends are in this sorority. And based on how they talk, I know most of the girls in the sorority are homophobic,which makes sense since it's all Christians.

Anyways, I'm trying to think of how/when to come out to people. I've started looking into housing for spring semester so I'd be able to get new roommates since I'm pretty sure they'll have a problem with me. But if I switch living situations that means I'm going to have to tell my parents first since they're helping me pay rent (I know, lame, but I'm working on getting a good job). So then that brings up question of when to tell the parents...I almost accidentally told my dad because I was talking about heaven/hell and how I feel like it's messed up that the church believes gays are going to hell. (This isn't a new thought I've had since I started questioning, it's actually because my aunt is a lesbian and she is one of the most amazing people I know and I can't imagine God rejecting her)

So I guess my question is...when and how should I tell my parents? What questions might they ask?

I've spent a good year almost (actually a year this Saturday) seriously questioning my sexuality. I know I am attracted to girls and I'm fairly certain I'm not attracted to guys (at least not sexually) so I guess another part to the question is do I tell my parents I'm lesbian even if I may end up being attracted to a guy later on, or do I just worry about that when/if that ever happens? Part of my problem is that I like facts and knowing things definitely and putting things in black and white but obviously sexuality isn't like that...so I am trying to date some girls, see how things go that way I'm hoping I'll have "evidence" as to why I'm lesbian (my only two relationships have been long-term with guys (one lasted three years, the other lasted a year and half). I did go on a date a little while ago with a girl and I was attracted to her but then she was on her phone the whole time so that was a let-down.

So now I'm on a dating website (only found one so far that was free, looking for some other free ones) and am trying to meet other singles in the area so I can get to know more girls. I really don't like the idea of online dating but considering I'm not out to any of the girls in my sorority and I'm pretty sure I'd get kicked out, it wouldn't be the best time to come out (not that there is ever really, so nervous).

So my rough plan for coming out is maybe before Christmas? I know, holidays probably aren't the best time but it is when I'll see most of my family. And in any event I don't go home a ton so there aren't really a ton of options of when to tell people. And then I guess for sorority sisters I don't really know, drop after this fall semester? I know it sounds dumb, but I feel close to a lot of these girls, and I'm kinda bad at making friends so it's not like I have a ton of friends outside the sorority. And I've been working on that, joined a Pre-Vet club, and we do have a LGBT center and I've been to that a few times but all the talk sessions are actually during one of my classes so I haven't been able to go to any of those this semester.

Sorry for the huge long ramble. Any advice/comments/ further questions about my story is welcome and fine.

Thanks