feeling angry/upset

Two weeks ago I gave up breastfeeding. I felt better almost right away but now I feel like I'm moving backwards and am extremely upset about how things went. I met with a lactation nurse in the hospital. She spent only a couple mins with me and told me to "be patient" even though my son did not sleep more than 30 mins at a time and was on my breasts for 60-75 mins at a time right from the start. My nipples were cracked and bleeding in less than 24 hrs. I met with another lactation nurse the next day and he had lost almost 10% of his body weight. She again just told me to be patient. I met with another lactation nurse two days later. She improved his latch but we were still having trouble with him gaining weight and he was still on my breasts 60-75 mins at a time and not sleeping. He would cry all the time.  I exclusively pumped for a few days so he could gain weight but I was getting really dizzy and forgetting to eat/drink water. It was too hard to keep up with his feeding schedule. I called the advice line to tell them what was happening and all I got was "breast is best, keep trying." She even had the nerve to say "this is the easy part, wait until he starts teething." After that conversation I just gave up and switched to formula. Since then he's been gaining weight, sleeping better and crying much less. I know the switch was better for all of us but I am so angry... I reached out over and over again and no one could help me. I desperately wanted to breastfeed and feel like I was robbed of that experience. I'm regretting my decision now and keep wondering if I should have just kept trying. But it's too late now. 
Just had to share this, it's keeping me up at night.