Thank you for sharing your experience BabaYaga. They said they'll give me two more weeks to accept the offer but her tone on the voice felt a bit irritated. She told me I should finalize my offer as soon as I decide so that they can give offer to other guys. They gave me extension but I'm kind of worried and nervous that they will revoke my funding. I don't think this thing will happen but kind of nervous because the April 15th has already passed.
The reply from UT Austin and CMU were also kind of negative. I'm thinking of waiting just one more week and then I'll accept the offer.