Hi there!
I am in the same boat as you ladies. I have always had irregular periods--I'm talking
months with nothing. I always figured I would have a terrible time getting pregnant (if ever) because of it. When I found out I was pregnant with my daughter, I was already 9 weeks! I thought I just had some weird tummy bug that wouldn't go away! Anywhow, that pregnancy came after three years of "not trying but not preventing." After I had her, I noticed I was getting my periods a little more often. When dd was about 2 1/2, I became unexpectantly pregnant again (basically we don't prevent, but we don't get "busy" too much either!). Unfortunately, I miscarried, but I really wasn't ready for another one, so I took it ok. That was in October of 2005. After the miscarriage I noticed my periods were coming even
more often. I really didn't want to get pregnant again, so I kinda "avoided" dh (he works long hours, and is always tired so it wasn't too hard

). Anywhow, I would have been due this past May, and for some reason when that time came around I started to feel the effects of the loss more, and began wanting another baby. I have never counted cycle days, and began to do so in May. Since then, my cd's have been--36-44-49-30-31-32-31. I was in shock getting cd's in the 30's for four months in a row! (I was taking a kickboxing class and working out a lot during the 44-49 day cycles, so I'm now thinking that had something to do with them being so long). Well, I started getting excited, especially when my friend gave me her Clearblue Easy Fertility Monitor, and for the past three cycles showed me o'ing on cd 16 or 17 (obviously all cycles ending in bfn's), but hey, maybe I wasn't so irregular after all! Well, I am currently on cd 19, and NOTHING!

(Don't pay any attention to the ticker!) I only had enough sticks to go up to cd17, and they were all "low". (If you don't know what the CBEFM is, basically you pee on a stick, put it in the monitor, and it will either say low (not fertile), high (estrogen is up, start bd'ing), or peak (here comes eggie!) Based on past months, I should have gotten "highs" last Thursday and Friday, and "Peak" Saturday and Sunday. I used my last stick Sunday, and don't want to buy anymore this cycle (they come in boxes of 30, and are pricey), so I went to the $ store and bought some cheapie ovulation sticks, but still nothing! I'm giving it until Friday to get a peak, otherwise declaring this a bum cycle. I
really would love an itty bitty baby this Christmas, but I don't want a December baby, so if this cycle doesn't work, I'm taking next cycle off and will try for a 2008 baby.

I kept thinking this past Christmas that we should be celebrating "baby's first christmas", but that for sure we would be in 2007. Well, it's not looking too good for that, but hey, there are so many people out there who are unable to have just one, so I am very grateful for the awesome dd that I have. It just gets frustrating to think that I go pg twice with basically no effort, and we have been bd'ing like crazy during the last few months, and all at the right times, and still nothing! And to make it even worse, my "normal" cycle streak is broken! My only glimmer of hope is that I have noticed a little more CM today (I have been pretty dry since AF left; sorry TMI), and my bb's have been a little tingly (I think--I could just be wishful thinking all in my head), which I've noticed they do around O, so maybe I'm just o'ing a little late. Anyhow, that is my story, and regarding the origional question, irregular periods can be a sign that you are not always ovulating, so it can definitely take longer to get pregnant. I've researched an herb--false unicorn root--that is supposed to help with irregularity "naturally", but have also found some unsafe info on it, so I'm passing on trying it. If nothing happens in the next few months, (and my cycles become irregular or if I don't get any "peaks", I'm going to see my doc and maybe he can help. I do really like the CBEFM, and it has been very helpful in understanding my cycle. It is pricey, but if it fits into your budget, it may be well worth it!
Good luck!