Aha

Finally got some answers! I had an ultrasound that confirmed that I have polycystic ovarian syndrome. It was pretty clearcut - 16 follicles on each ovary, when I think the typical number is one or two. But the diagnosis is weird:

1. It's a kind of chronic long-term syndrome that usually crops up in early adolescence, not something that you develop later. But I had regular periods for years before I got pregnant the first time, and I didn't have trouble conceiving then. Why would I have developed this syndrome after my first pregnancy?
2. Often a pregnancy resolves the condition. In my case, it apparently triggered it, which makes no sense at all.
3. Some of the hallmarks of PCOS are being overweight, being diabetic or borderline, and having excess body and facial hair, acne, and painful periods. But those don't apply in my case (hmm, maybe the acne a bit, but it's not too bad). I guess I am an atypical patient.

At least I have a diagnosis. It was so hard not knowing what was going on and having to fend off suggestions like
"maybe you secretly don't want a baby, and this is your body's way of telling you"
"just adopt"
"maybe you're not trying hard enough"
"maybe you're trying too hard"
"maybe you're not 'doing it' right"
"oh well, it was easy for me"

The last is probably the one that drives me craziest. Some people have full, interesting, busy lives - they're advancing in their careers, traveling, doing home renovations, and still manage to get pregnant in their spare time without really trying. In my case, I've gone to soooo many doctors' appointments - expensive and time-consuming. I've been trying to relax, eat better, change my exercise routine, etc. all in hopes of improving my fertility by reducing my stress. And I'm still nowhere near the point where they'll be able to start treatment, let alone the point where I might achieve a pregnancy. It bugs me that some people have it so easy and apparently don't understand how hard it can be for others.

The standard treatment for PCOS is birth control pills (and as soon as you discontinue the pills, the syndrome comes right back). Obviously I don't want to do that. I have to do some more stupid tests now before I can schedule a consultation with my doctor and renew my requests for Clomid, the ovulation medication I've been asking for for a year. I hope he'll prescribe it. I read that patients with PCOS have a much harder time getting pregnant and have a 50% miscarriage rate (compared to the normal 15-20% rate), which is a bit scary, but I don't think there's much I can do about that. I just hope that in that area, I'll also be an atypical PCOS patient.

Update:
I talked to my doctor today. He said that the average number of follicles in a healthy ovary is 10-12, and that he'd rather see too many than not enough. So that makes me feel a little... well, closer to normal. Here I was thinking I was some kind of monster freak with my 16 follicles on each side.

I also underwent an HSG today (hysterosalpingogram), in which dye is squirted up through the reproductive tract to outline the uterus and fallopian tubes to make sure there isn't a blockage. Everything looks fine in my case. I was amazed to see that on the left side, the fallopian tube does a loop-the-loop! The doctor said that was perfectly normal and that the ovaries and tubes actually move around a bit in the pelvis and often are in unusual configurations, not just out to the side like the crosspiece of a capital T. Still. A loop-the-loop! Those little eggs have a long way to go on their roller-coaster ride to the uterus.