If you've got your NCOs constantly telling you that you can't do something / something is impossible...well, let's just say that E1s are impressionable. It's entirely possible that he now feels that six months without you is too long for him, and that it would be unfair for him to ask you to wait that long. I dunno...I never had this issue, but I've seen it be an issue before.
MOS? In my mind, MOS stands for Metal-Oxide-Semiconductor.
Military Occupational Specialty. I think she means AIT, which is Advanced Individual Training where a soldier/marine/sailor/airman learns the skills necessary for their MOS.