Just to clarify, stress won't affect your supply (it might affect your let-down, so yes, it's great to relax, but how do you think mothers manage to bf through war, grief, hardship? Our bbs still keep going!).

The best thing to improve your supply is to feed, feed, feed. What you did last night is exactly right, but you might need to do it for longer than 12 hrs. 60 mls is not very much for her to take, so she must have had a fair bit from you during the night. Try doing exactly as you did over the night, but for an entire weekend. Do it when your partner is home so that he can support you, bring you drinks and food. It can take a few days for your supply to catch up to the extra demand, but you will get there with this kind of persistence.

GL! I really admire your perseverance. And can I just say, 60 mL expressing every 2-3 hours is great for someone who hasn't been expressing for that long and who also bfs in between!