I had a d&c because i had a missed miscarriage about 3 months ago. now in the last 6-7weeks i've had my period 3 times ?

Sometimes it does: happen because your cycle is disrupted and dysfunctional for few months. so if the cycle does not correct itself in 3 months then you may need treatment. in the interim just make sure you are not pregnant

Irregular cycles: It is normal for a woman who has gone through the physical and emotional stress of a miscarriage to experience irregular bleeding for a few months after the event.