Post miscarriage

Ok so I was about 12 weeks and had a miscarriage and ever since my periods have been way off compared to before. Before my periods were spot on lasting 7 days, now they are nearly regular but they don't seem to last. my last was only about 3 days long with one heavy day and then spotting. Has anyone else had this problem and how long after a miscarriage did it take you to get pregnant again?