Fertility differences: Peanut vs Bugabug

I've said before that we tried for 14 months to conceive Penny, and now with this baby, it took, like a day. Anything over 12 months of trying is technically considered infertility, so I went from being an infertile to a fertile myrtle. So what's the deal? Obviously I don't know for sure, but I thought it might be interesting to muse about the differences. Here's what I can think of that may have impacted my fertility.

1. Hormonal birth control. This time around, my body hadn't been exposed to hormonal birth control in over 3 years. Last time around, I had been taking the pill for 5 years before we started trying. I think some people's bodies respond differently to hormonal birth control, and I think it is way more common to have trouble "bouncing back" than I was led to believe when it was prescribed for me.
2. Circle + Bloom. This is a totally crazy story. So I looked back in my email to see that I ordered my copy of C+B on March 7, 2010. That was after ovulation in a cycle that didn't result in pregnancy. I got pregnant in the middle of April, 2010: the very first ovulation that I used C+B. We'd been trying for 14 months. Used C+B once–pregnant. After Penny, my period came back in January, a year after I gave birth. I just sort of kept an eye on things in January, February, and March of this year. I was charting to see what was going on with my body, but we were hoping to have our babies be at least 2 years apart. I started a cycle in the end of March, and we decided to go ahead and start TTCing, since we figured it would take awhile again. I dusted off my C+B tracks (figuratively–they were loaded on my iphone) and listened to them during that cycle. Pregnant. So two cycles of using C+B. Two pregnancies. Of course this could be a total coincidence–I can't rule that out, obviously. Or it could be that my body really responds to this stuff. Mind-body visualization definitely helped me during labor, and I like to believe that it helped me to conceive as well. Here is another post I wrote about C+B. 
3. Chiropractic care/acupuncture. I started seeing a chiropractor in March of this year. She provided chiropractic care and acupuncture, for general health, to support fertility and to support my thyroid. I had never seen a chiropractor before, and I had only gotten acupuncture once before, which was after Penny was born to help with my milk supply. If you aren't familiar with chiropractic care (it seems to be more popular in certain regions), it is designed to ensure that you have a healthy nervous system, which impacts every function in the body. Through everyday bodily stresses and abuses, the nerves in the neck and spine can get pinched or twisted or out of alignment, and chiropractic care ensures that the nerves are healthy and aligned so that all of the body's systems can function properly. That's my layman's understanding anyway. If you're curious to learn more, contact a chiropractor in your area. This may have made a difference for fertility, but it definitely made me feel awesome, and I plan to continue chiropractic care as a health maintenance practice throughout my lifetime. It's covered by insurance too, which is awesome.
4. Thyroid support. I started taking thyroid medication in January 2010, 2-3 months before I conceived Penny. I have been taking it since: a very, very low dose of naturethroid. My thyroid was never super low-functioning, borderline at worst, but perhaps the thyroid support was just enough to boost my fertility.

I would say that those are probably the most likely factors that made a difference, but here are a few other differences I can think of.

1. Toxicity. In the last couple of years, I have been making a huge effort to reduce the chemical load in our house. I've been vigilant about buying the right foods and avoiding conventional household products, cleaners, cosmetics, etc. This started right around the time I found out that I was pregnant with Penny, so it is possible that my body was more willing to conceive a baby when it wasn't being inundated with all kinds of junk in my environment.
2. Food. I read Michael Pollan's In Defense of Food in the summer of 2009, about 9 months before I conceived Penny. That book sparked my journey towards a whole foods based diet, but diet is hard to change and doesn't happen overnight. I am still working towards this and struggle every day to make good choices. In the months after reading that book, I made a very concerted effort to eat "clean", avoiding processed foods and hormone-ridden animal foods as much as possible. However, with all of the vague labeling, it really takes some time to figure out exactly what is okay to eat, so who knows how good I was at that time. About 3-4 months before conceiving Penny, I went gluten-free, and I think at that time I started to lax about eating clean. I could only focus on so much at a time, so I'm sure I was eating some gluten-free junk food. This time around, I was eating gluten (whole grains only), but I was extremely strict about only eating grass-fed, local meat and whole foods. My diet was very clean, and I was mostly following the anti-inflammatory pyramid except very minimal soy.
3. Expectations/stress. I think I had a much healthier (and realistic?) attitude towards TTCing this second time around. I just knew so much more about being patient this time and was prepared for it to take awhile, so my expectations were lower, and I put less pressure on my body. The first time, I expected everything to go perfectly as soon as I was ready to start trying, and by the time my body was able to shed all of the BC hormones and junk, I was so stressed emotionally, that I think that got in my way and stretched out the process. 

That's all I can think of. Have any of you had drastic changes in your fertility? Can you guess the reasons?