Please help with breast feeding.

My babies 7 weeks old I've been only breast feeding and pumping, trying to build my supply up for when I go back to work, lately it seems like I'm not producing enough in the evening to the night. I've been doing power pumping where you pump 10 on each boob for an hour once or twice a day. I pump after each feeding to really empty my breast for the past 2 3 days and it still seems like I'm not making enough for her 😢 and she'll cry on the boob with it in her mouth, I don't want her to starve so I heat up some saved breast milk and give it to her in the bottle. Am I drying? Is there any way to stop myself from drying up? I want her to be a breast fed baby please formula is expensive. What do I do??