How many times should you try to get pregnant before you give up? That's a really tough question. Listen to your heart.
Of course, almost everybody tries the "normal" way to get pregnant first. That works for most people, too, especially if the woman is young.
Some people jump right to assisted reproduction--such as single women who want to have a child alone. Others end up in assisted reproduction because of diagnoses, such as cancer, or congenital problems like undescended testes or uterine abnormalities. Or, of course, because the normal way didn't work.
I remember talking to a reproductive endocrinologist, and he had just done an egg retrieval on a 20-something year old woman who had lymphoma. She wanted to preserve fertility for the future, but sadly, she was not doing very well at the time, and the doctor commented to me that saving her eggs was probably a waste of time. I said, "If it gives her hope and something to dream about, it's not a waste."
That is how I feel about any of these procedures that you might consider--if it gives you hope, then give it a try, as long as you can.
But how long is too long to keep trying? That is an individual answer. Some couples can go through IVF many times and ultimately succeed. Others will never succeed, but in the beginning, nobody knows who will and who won't get pregnant.
The science of conception is poorly understood. While reproductive endocrinologists grade embryos, the truth is that some "ugly" embryos make very beautiful babies. Statistically, the higher the grade of an embryo, the more likely it is that pregnancy will result, but doctors know better than to say that an embryo has no chance at all.
It's that fact that keeps some couples going during an IVF attempt where poor quality embryos were produced. Also, one IVF cycle may result in poor quality embryos, but the next cycle will result in perfect embryos and a pregnancy.
My answer when I'm asked about how many times people ought to try IVF to get pregnant is this: As long as your heart can take it. I met a woman who finally got pregnant with twins after multiple failed IVF cycles. She and her husband had almost given up as the money dwindled. But they decided to try one more time because they decided that they wouldn't always have the chance to make children, but they could always find a way to make more money.
Have hope, friends.