I think retroverted uterus is different to tilted cervix. Everyone's uterus is tilted either slightly forwards or slightly backwards; it then straightens as a baby grows inside it.
I found out at my smear in February that I have a tilted cervix, and it was agony to have the smear because of this. However, when I went to the GP who specialises in sexual health to have my coil removed, she didn't cause any pain at all because she is more expert.
I have done a lot of research since being told about this, and also asked the nurse at my smear. Apparently, the best sex for baby-making when you have a tilted cervix, is doggy style! Also, yes, lying on your tummy can help. She said that carrying and giving birth to children can be more painful/problematic but that in most cases it's fine. It is also very common.