I don't want this to happen...is that bad?

So, it's D-day. Meaning today is the day the high school kids are suppose to let me know if they REALLY want to go on a Mission Trip to Iowa where we will help gut out houses affected by the floods last year. I said we would do this if we got five kids. So far we have 3. I just reported this at a staff meeting. The priest said, "You really need to try to make this happen. It would be huge if you did. Extend the deadline, call people do whatever you can." And, I know this. This has never really been done here at this parish in the past. I know that if we do it once it could turn into a permanent summer event. It could change the lives of these young people, we could do a lot of good. BUT.. I don't want to do it! I think I've been kidding myself all along thinking that it WOULDN'T happen because we didn't get enough kids. To be honest I wasn't trying that hard. Why don't I want to do this? First of all I am SCARED! A father in the parish has already volunteered to be the male chaperon and he would be great. BUT I have never taken teenagers away for a week by myself before. And let's face it, teenagers can be a handful. I love teenagers but there's no telling what kind of trouble they can get into. I remember the mission trip I took in high school where kids brought pot along (they got busted by the way and we were never able to go back to that town again!). I'm also scared because I do not know what I'll do if I'm pregnant. And I want to be pregnant so badly and I don't want to have to worry about it. I really don't think pregnant people can muck out houses with mold and goodness knows what else is growing in it! Also, I don't really want to give up a whole week of my summer away from husband, pregnant or not. What kind of job that only pays you $30,000 a year asks you to spend so much time away from your loved ones? I mean its not like I'm some high powered business woman being asked to travel somewhere for a meeting. I feel so bad about not wanting this to happen. But its true. It makes me feel like I'm in the field. This is what ministry is and I just don't have it in me. I think it would be easier if I was single. Maybe I'm just crabby because of PMS or hopefully pregnancy hormones. Sigh! What to do what to do?