I've had the same problem in the past chronically. Went to many Dr's who just said it's IBS, take fiber, etc etc The only thing that's truly helped is seeing a holistic practitioner who has me taking small doses of Polar Mins (all products I mention besides Cell Power are by Premier Research Labs) mixed in plenty of water (it's very concentrated with minerals) each day along with 1-2 capsules (or more) of Premier Magnesium. Make sure to drink more water throughout the day also as the magnesium draws water to the bowels.
If that still doesn't make you regular, try taking LaxaGen, also by Premier Research Labs. It's a natural laxative that is meant to be used long term to help pull crud off the walls of the intestines over time and get your bowels moving. Unlike other laxatives, it is safe because it is totally natural and pure.
Another great product to try is called Cell Power by Positive Power. Similar to the Polar Mins, it is concentrated with minerals (such as potassium and magnesium which help bowel regularity), and it also oxygenates your body which is helpful in balancing your ph levels which will help in all areas of your health. Start small with 5 drops/10 oz water a day and then after a week, check your ph using urine ph strips (can be bought online). If you are not within 6.4-7.0 urinary ph range, up your dosage to 10 drps/20 oz water a day. Check again after the second week, etc until you are 6.4-7.0
I know this is a lot of info but it's important to take charge of your health and not let problems multiply and become worse problems down the road. Good for you for seeking out others with a similar experience and best of luck to you! Let me know if you have any questions as I now work for this holistic practitioner so I have learned more over time