You're doing a fantastic job hun. Try not to worry about how much you are getting - in fact if you manage to not measure it at all it might help you relax - which in turn will help you get more out. As long as you are expressing regularly you will maintain a good supply until you can feed again. And if your supply needs a boost then your little one feeding will achieve that pretty quickly. Keep up the great work and try not to stress. I know that's easy to say but you are already doing so well with all you've been through so I know you will fine