bowel problems since i was a toddler

I have had problems since i was a toddler with going to the bathroom

i always have a tendensy to ignore my bowel movements and hold in my stool until it hardens and becomes difficult to go to the bathroom, now it is to a point where it is physically impossible for me to excrete my wastes, i will feel like i need to go to the bathroom, but then the second i sit on the toilet it just doesn't work for me, this past summer i had a bad marijuana problem and due to that i had frequent diahhrea and pains in my stomach/bowel areas. i do not know what to do, this is stressing me out tons and i wish that this could stop, my eating has been consisting of lots of fruit, some oily foods like pasta, fried chicken, lots of soup, and fiber cereals. please if anybody has any advice for me i would so gladly appreciate it, thank you and i hope to hear from you all soon