You're thinking waaaay too far ahead and stressing too much.....take this one step at a time, that's my advice.
Just focus on getting through nursing school #1.
Then when you're done, next focus will be on mastery of basic nursing care in the real world. THEN if you are still motivated to go on to critical care, focus on becoming the best ICU nurse you can be. This stuff doesn't happen overnight, so slow down a little and enjoy the process.
Once you are an experienced critical care nurse, get your CCRN. And maybe your CEN (working a little ER never hurts either, for those emergency situations and difficult intubations) I'm not a CRNA but know quite a few (who worked with me in ICU prior to CRNA) They tell me these credentials are looked at very favorably in the selection process, at least in my area.
Hint from an old ICU nurse: ICU nurses tend to be a tads put off by the introductory statement 'I'm only here to become a CRNA'. This pitstop attitude will NOT endear ya, believe me.
Things will all work out if they're meant to. You may find yourself heading a whole different direction once you're a practicing nurse. Happens all the time.
Good luck to you, and relax and have a little fun when you can, as we're only young once. :roll