You haven't failed at anything. Have a good time on Saturday, nobody will be judging you.
I know that for you four cycles is a long time and that can be very scary but with your average of conceiving so quickly I am sure you will get a bfp soon and maybe it is taking longer because your body needed to work some things out and this time it will be a super-sticky bfp. Hang in there and stay positive. :)
I'm out too this month. Better luck next month. Hope you're having some fun times.
I'm so sorry to read that you're going through all of this & then to top it off you're having to meet the extended family - well, that's a lot of stress to put yourself under. Remember, it's not over yet - hang in there - it will get better! - jen