Can D&C Causes Irregular Periods?

hello doctor.i found out that i was pregnant on 1st december 2009 and had a d&c procedure done on 7th dec 2009 at about 5 weeks.i had some bleeding after the d&c.after that i got my first periods on 7th january 2010 which was normal as before.i was relieved.but i was due on 7th Feb again but i didnt get my periods yet.i am 10 days late.i did a pregnancy test but it is negative as off now.i did have unprotected sex(used the withdrawal method).i do not wish to get pregnant again.please shed some light on this.thanks