I cannot go #2, and am full of stool.

I can't go #2. My stomach is so distended that I look pregnant, it hurts, I'm always full, and tiny amounts of food make me feel stuffed. My doctor told me to exercise, drink Miralax and lots of water, and eat lots of fiber. I've been doing this for a while and it isn't working. My diet has contained tons of fresh fruits, vegetables, and 100% whole wheat and grain. I also did 2 enemas which did not work, and I took laxatives and milk of magnesia which did. There was a LOT that came out, yet there is still tons of stuff in me! My doctor referred me to a Gastroenterology place, but it's completely booked until July. Nothing else takes anyone under 18,I am only 16. Another odd symptom is that I'm bleeding two weeks after my period, and it's brown not red. No, I am not mistaken. Also, for the past couple of days I can go every so often if I strain really hard, but it comes out pencil thin. Basically a few pencil thin (maybe an inch 1/2 in length) pieces of stool is all I can squeeze out.