You need a thorough evaluation for your condition. Bleeding in between periods and irregular periods can be due to several causes. The commonest cause of is hormonal imbalance. The two hormones regulating a woman’s cycle are estrogen and progesterone. If they get out of balance, one may have spotting. Pelvic inflammatory disease, STIs, atrophic vaginitis, cervical or endometrial polyps, cervical erosions are few common causes of bleeding in between periods. Delayed periods can be due to ovulation dysfunction, thyroid disorders, hormonal imbalances etc. Depending on your detailed symptoms and medical history your doctor may recommend a pelvic examination and other tests .Only after a detailed clinical evaluation the cause can be determined. Hope it really helps. Do keep us posted.
Take care and regards!