Make sure you are getting probiotics in your system, even the yogurt enriched with them will work.....eat one a day. Fiber, and plenty of water. Miralax which is a stool softener can help as well and it's not habit forming. Make sure you get plenty of exercise as well.
You sound exactly like my condition was until 5 days ago when I finally made the decision to have a colectomy which is a removal, resectioning they call it, of a section of your colon.
Mammo makes great suggestions, I tried them all except the exercise. For her tips to work, you must do them all. Good luck and remember that elective surgery is much easier than a severe occurrence that may require a colostomy.
Water is so important, the more the better. Water is definitely your friend. I found Peri Colace Stool Softener and Stimulant Laxative (the combination of the 2) to be effective, about 3 or 4 times the price of other laxatives, but proved worth it for me. Don't hesitate to take 3 or 4 pills the first time. Some discomfort but a lot of relief. Good luck.