Your CO is not only working your case, but also the rest of her caseload, probably about 100 other files, in rotation. From what the call centre said that she is putting notes on your file, evidently she has been checking what you sent. Probably she has to send for more information, then await replies from other people. In between times, she does the same thing for the other cases, too, and will not see replies concerning your business until your file's next turn for her attention. She will have nothing to tell you until the process is completely finished.