I get bad pains, flooding, late and heavy periods, sometimes I am unable to move because of this, how can I reduce the pain or stop it?

Know your options . The cause of the heavy periods is not something we can always answer. There are lots of treatment options you can discuss with your doctor. Lysteda is a nonhormone medication designed for heavy periods. Some benefit from birth control pills, patch or nuvaring. Mirena (levonorgestrel) iud can stop your period in some cases. Consider an endometrial ablation if you are done having children.
Birth control. I reccomend some type of birth control for cycle control; this can include pills, shot, and/or iud. I also reccomend starting nsaids like Motrin 1-2 days before menses for better pain control.
Birth control pills. Most women will respond well to cycle control with bcp's. Even if you don't need birth control (if you have no contraindications) it is ok to take bcp's just for cycle control. Most women on bcp's will have lighter periods, less cramping, less clotting, and better cycle control. If that doesn't work there may something else going on such as polyps, fibroids, infection, or endometriosis.
Many choices for you. Abnormal periods need evaluation; sonogram, lab tests. Non-surgical options include: birth control pills. Lysteda (non-hormonal rx taken during period), Mirena (levonorgestrel) iud. Minimally invasive options: endometrial ablation (in-office), hysteroscopy polyp removal or fibroid resection; and only if these treatments fail then consider hysterectomy - vaginal or laparoscopic if possible.