Don't get too discouraged if you are not pregnant after only 4-5 months. My friend found out she was expecting in December, and they have been trying for 2 years.
When there is such a small window each month for pregnancy (just a couple days, tops) it is really hard to hit that exact point of time in a given month. When you are trying for 4 months, for instance...really there is only about 8 days of fertile time there.
It's luck of the draw, really...sometimes you get lucky, and other times you don't. It will happen when you least expect it to.
