Morning Gertie, I am not entirely sure but here goes (only my unqualified opinion)
After an abortion the body goes through many of the hormonal changes that giving birth does. So it could be normal not to have a period. I had an abortion many years ago but cant quite recall how long it was before I was 'normal' cycle but I am thinking about 6-8 weeks.
Also the stress of the abortion both mental and physical will have an affect on your body.
I would advise you to contact your GP and discuss this with them, I am sure that it is pretty normal for there to be some delay (everyone is different) and most importantly this will put your mind at ease.
take care
warpig