I know this is an old thread but I hope this might bring you some peace or comfort:
The spiritual theory is that the souls of babies who are lost through termination or miscarriage go back to wait for their next chance to incarnate with their mother. So your children would be / are the souls of those you lost.
Also, that before (re)incarnation, we choose what lessons we need to learn in our next life to help us evolve upon our spiritual journey, which explains why some children are born to terrible parents and into terrible circumstances.
Likewise, sometimes some souls choose to reincarnate into certain lives because they will help another soul on their spiritual journey - so a soul will fulfil an unpleasant or sad part in someone else's life because of the life lessons one or both them need to learn.
And it follows that when a woman finds herself childless after miscarriages or terminations that it isn't a punishment, but another soul chose to incarnate with them for a very short time (because, life lessons).
Please, please don't think that you were ever unwanted.