Hello! I totally understand the frustrations, we had the exact same thing happen with constipation and potty fears (or as we called it - the potty wars) with my oldest daughter who is now seven. Sometimes, even with a supository, she would go up to three days without a BM and then I would have to do the dirty work for her to help it out!
Try to battle one thing at a time. She is probably not letting go of the pacifier because she feels like she needs some extra comfort and support during this difficult time.
Let go of the potty too and make sure she never feels any sort of "pressure to preform". Careful with the added fiber - i know it may seem counter-intuitive but it can actually cause some people to back up if given too much. You want to not only battle the back-up but also the behaviour - it probably hurts because the poop is so hard and compacted so she holds it in - then it gets hard, etc.
Make sure she is getting LOTS of water and try to add olive oil or a high quality fish oil supplement to her diet. Another thing that I found helped - ground flax seed. Throw some of that stuff in some applesauce or yogurt and it makes a big difference. A surprise I found also was that gummy bears seemed to work! Perhaps everytime she has potty success you could give her some gummies - support both body and mind! There are great gummy vitamins out also that have no sugar and are sweetened and colored naturally and I have found that to be great for my kids. If all else fails and you are willing to give it a try, add a small amount of coffee to a glass of warm milk (maybe with a little sugar) - That will move those bowels quickly!
Last but not least, try this recipe for puerto rican style rice and beans - i know rice is supposed to "stop up" (BRAT) but man I have never found something to keep my kids more regular!
make a sofrito with handful chopped cilantro, half medium chopped onion and three chopped garlic cloves. Sautee in olive oil until softened about 7 minutes. Add salt or a seasoned salt like Adobo and about 3 oz of tomato sauce and simmer another 5 minutes. Add a can of red beans with liquid, fill can with water and add to pot. Simmer on med heat covered for about 45 minutes to break down any undigestible sugars from the beans. Heat rice (2 cups water for every cup rice) and serve beans on top of or mixed and mashed with the rice for kids - make sure you use a lot of the bean liquid. Use as a side dish for your favorite main course! Enjoy!
Good luck!