Chronic constipation in lo

Looking for suggestions. My lo is almost 9 mo now and she has had chronic constipation since 2mo old. Tried breastfeeding at first and after exhausted ALL avenues to be successful had to resort to formula. Talked to her doctor multiple times and she pretty much waves it off but I'm tired of my daughter screeching in pain when trying to do her business. Have used Gentlease formula, Enfamil AR when had reflux as well, Gerber soothe, and now Alimentum as thought she may have milk protein synsetivity. I know it's normal for some babies to not poo for 3-4 days but when she does go after that time frame it is hard green or dark pebbles and sometimes large balls but only passes few at a time. Have given apple juice every day,feed prunes regularly, and given small amounts of water through day. Done bicycle kicks,tummy massages,tummy time,warm baths, and now resort to infant suppositories. Anyone in the same boat and could recommend anything else to try?? Anyone given any advice from your pediatrician and is your lo this sever with constipation?