Chronic Constipation for Years, Please Help

Here is some info on my situation, any help is greatly appreciated.

-Age 20
-Female
-H: 5'6, W:150
-I can remember having this problem for at least 8 years now.
-I went on Birth Control when I was 13 for acne problems. I am still taking the same one now: Microgestin FE
-I have talked to my doctor about this for at least 4 years now. She is very unhelpful and forgets me so each time she just recommends that I take fiber (or miralax). I have tracked my diet for weeks and I get plenty of fiber a day (at least 25 grams). I am vegetarian and I only eat whole grains, veggies, beans, oats, fruit, etc.
-I only drink water. I carry a water bottle with me everywhere and I don't think that I am dehydrated.

Here is a description of my problem:
-I have not had a normal bowel movement in years. If I do it is always rock hard pebbles or diarrhea.
-I am always bloated and very gassy.
-I have difficulty having a bm even if I feel like I have to go.
-If I look at the opening to my anus, there are purple blood vessels around the opening. I don't think these are external hemorrhoids because they aren't painful but I'm not sure if they are normal.
-There is a small dimple in one part of the opening to the anus.
-There is dark yellow mucous on my stool.
-If I try to push like I am having a bm the opening is not clear, there are different bumps that I can see (not like on open hole) and I'm also not sure if this is normal for the anus.

Sorry for so much information but I really need answers. This is such an uncomfortable issue and I don't know what to do anymore.

Any ideas on what could be causing all of this?
Any ideas on how to treat this?

Thank you.