First of all, I really admire you for your effort! I'm guessing it must not have been easy.
While I do not have any personal experiences to share, I found this article that you may find useful:
http://exclusivepumping.com/sample-pumping-schedules/
It offers a sample pumping schedule that may help sustain your supply (see the second section for schedule for older babies). Also, I've read that the usual suggestions to increase supply also applies for exclusive pumping mummies. For example, pumping more frequently, drinking plenty of fluid and having a balanced diet, plenty of rest, and trying supplements such as fenugreek and oatmeal etc.
Hang in there and hope you find something that worked. Long term pumping is possible (from what I've gathered over the internet). Take care!!
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