Throw in the Towel?

Hubby and I are trying to decide when to call it quits with the IUI. We've done three this year and none have been successful. The last one was actually called off as I ovulated on my own and it was too late to do the insemination. Guess we are both frustrated with the situation and going through the process of an IUI, which brings with it a lot of stress and I become an emotional rollercoaster from the hormones. We've been on a 'break' the past couple of months from visiting the RE and doing the needles and sonograms etc. Honestly, I've been really happy and relaxed for the first time in about a year...The last time I felt this great was before my miscarriage in spring 2006. I love my life right now. Sure, I would welcome a baby if that happens naturally, but I don't think I want to go through with more fertility treatments. Also, I'm a bit scared about the long-term effects of the hormones on my body. It would be so much easier if pregnancy would happen easily and naturally like it seems to do to other couples.