Anyone have advice with increasing milk supply?

I went back to work when my daughter was almost 8 weeks (now going on 14) and ever since then my milk supply has died. I used to be able to pump 5oz at a time even while breastfeeding. Now even when it's been 3 or 4 hours since last feeding I'm lucky if I get 2. She drinks 4oz bottles at a time so it takes me 2 to 3 pump sessions just to get her a bottle.

I work 6 and a half hour days at work, and I pump twice (although before this week I was only pumping once) and I'm drinking mothers milk tea to try to help. But we've had to supplement quite a bit when I'm at work and I don't want to anymore.

I'd love to hear from any of you who have struggled with their milk supply and what helped. Thanks 🙁