I think many schools are competing for the same set of top students. Waiting to hear back from the top selections probably adds a considerable amount of time to the decision process for less-than-top students. I doubt that the admissions committee is intentionally making the process as long as possible. Its hard work selecting students. I actually think its good that the whole process takes less than 4 months -- I've had internship/research applications that took longer!
I'd try to wait it out a little longer to see what NASA offers you. I'd also go where the funding is definite, otherwise I'd have to spend more time agonizing over the possibility of not getting a fellowship. That's just me.
I'm the same! I've been neurotically checking my email, reading and re-reading the FAQ's about when decisions will be made. Its so awful!!
I'm glad to know I'm not the only one physically upset by this process.
Field: Statistics
Applied: UC-SB, UC-Davis, Texas A&M, CSU