Hi,
Thank you all for your advice.
I showed the quilt to my nephew and his family and they did not even notice the seams!!!
So I guess I was indeed being too critical of my own work.
I did use bright white polyester batting (Hobbs 80/20 cotton batting made my white fabric look yellowish) so the problem was caused by the grey backing fabric.
But hopefully the seams will not be as prominent after it has been quilted.
After reading your comments I have decided to leave it as it is and finish it.
In this picture you can see the whole quilt with a part of the backing fabric showing.
Please don't look too close at all the wrinkles ...it is still a work in progress...
Thanks for your help.
Katie