I don't know anything about a tilted uterus, but I do know that "doggy-style" is supposed to be the deepest position. Therefore the sperm are deposited the closest with the highest chance of conception. Then afterwards you should lay down for atleast a half an hour with your butt proped on a pillow. Hope this helps. It's all I know.
I've read a lot about this and generally speaking, a tilted uterus should not hinder your ability to conceive. Grant it, I've been TTC for 8 mos with no luck, but supposedly my tilted uterus is not to blame. I have read that rear entry is good, but I also know of women that had luck with the missionary position.