How do I get semi regular bms when on narcotics or aleveate some of the constipation? Natural options? What laxatives are better than others?

Hydrate! Make sure you drink plenty of water, remember any fruit that starts with a "p" help you have a bm, peaches, plums, pineapple etc. Try to get some exercise, as you are allowed to. And consider magnesium as a stool softener. Check with your doc!
Constipation from Rx. Assuming no structural abnormalities nor inflammation of the bowel, constipation as you describe is likely due to altered GI transit by narcotics. Adding fiber may serve predominantly to fill the colon, not improve laxation. Use of irritant laxatives may cause "cathartic colon." unless your narcotic requirements can drop, you may need prokinetic &/or lavage agents to improve transit & emptying.