Withheld stools as a baby, child, adolescent? WHY? Causes and affects??

I just recently read about this, and am so curious about it. Since I can remember, until I was around 12, I would "hold in" my stools.  It was all I thought about, and did everything I could to avoid going to the bathroom. I wouldn't have any accidents, as I read about others, "soiling." I was just so afraid to go, because one time I went to the bathrom and it had been probably a month, so the stool hurt my bum.  I don't know if thats how it started, but this continued on well into my early teens.  I would have to go, try to sit, but then freaked out, and would hold it in. Usually I would hold it in for 2 weeks-6 weeks.  
I would also lie about "being constipated," or self-inflicted constipation, that is. I would lie to my parents, and didn't want anyone to know! I was very mortified about it.  I would have to have mineral oil almost every day, suppositories, enemas, laxatives, you name it. The worst of it was when I was about 7 years old.
Everything was fine physically, thank god.  As I got older, I am able to go to the bathroom(BM) at other places, but am very embarassed when I do! Help! Answers!!
But I want to know what was going on?