Supplimenting

Ok so this is my first baby and I've tried my hardest to give her breast milk the whole time. She's 3 months old now and I'm still pumping, but I can't get ahead of my babies eating schedule. I pump for 30 mins every 3 hours ans she wake up to eat every 2. If I don't make at least 4 oz, she cries for more ans lately I've been making between 3-5oz. My doctor has recommended I try fenugreek to increase milk supply which has worked, but am still only making one bottle ans honestly I'm getting very overwhelmed with trying to continue to breastfeed. By the time she wakes from her nap, it's time to pump again and screams bloody murder almost the whole 30 mins it takes to pump, which of course affects how much milk is produced. It's almost impossible to calm her while I'm pumping. So basically, my question is if anyone else is having a similar problem. I'd love to give her breast milk the whole way but it's getting to the point of panic attacks when she cries like that and I need to change. Not to mention i cant go anywhere (grocery, familys, doc appts) longer than an hour cuz I have to get back to pump. Her doctor recommend to suppliment but now that I'm considering it, I'm not sure how it's done. How much she eats compared to breast milk? How often? If I give her formula, will she refuse the breast milk? What brand/kind of formula to get? I'm waiting for a call back from her doc, I'm just wanting to get others insight. Breastfeeding has been a personal nightmare for me but I want my baby to have the best so I'm still trying. Now it's affecting her too so I need to figure something out.