Yes, I had to. I would pump every three hours, same as feeding her until my supply came in then three hours during the day and whenever it hurt at night. We filled her bottles the night before and kept them in the fridge and then just put them in the bottle warmer to heat them. Usually after feeding her I would pump for 15-20 minutes. I had a pump that did both sides at once, which I highly recommend. By three months she wasn't a strong breastfeeder and I was losing my supply, so when they told me I needed to feed her for 40 minutes and then pump for 20 I decided it was best for both of us if I just pumped exclusively. Pumping exclusively was way easier and it allowed me to stay sane. My next one I'll try to breastfeed again, but if I have to switch to pump exclusively again, there is no reason I wouldn't.