Am I Too Old....

A little background first. My father was an older man who had a very rare illness (go to http://www.alpha1.org/ to learn more), because of my experiences I told myself I would have my kids young.  My cut-off age is thirty.  Pregnant by twenty-nine.  Give birth by thirty.  No more babies after that.  The dilemma is that there is a big age gap between my first two kids (one is 2 and the other is 9) and I would like to have another child, but I only technically have this year and the next and then done.  No more.  I'm not sure if I'm ready though. I had an emotionally trying pregnancy and have worked hard over the past 2 years to overcome that, and my second child was a VERY difficult baby. So I guess the dilemma is do I go against a very strong conviction that has been with me for years, and wait until I am ready, but possibly live with the regrets of having another child "too late", or do I get pregnant now even though I really don't want to and may not be emotionally ready to.  Let me just say I am very convicted about the over 30 thing, mainly because of my upbringing.  There are two very strong emotions at play here and it feels like time is running out. Any of you have a similar timeline of when it is too late to have kids, and do you have any specific reasons for it?