It's sort of repulsive, but here's what I saw (the top bit of fur is her tail; side bits are her thighs):
So, after talking to Dad and some research on the subject I realized that no, she isn't pregnant; yes, she is fine; yes, this is all very normal. I also got some bad news: no more runs or dog park visits with Heidi while she's in heat. Turns out that male dogs can smell females in heat from miles away and will go to great lengths, even harming themselves, to mount the female. I'm going to steer clear of all that jazz.
Having a female who isn't spayed can be messy. Heidi has done a great job keeping things tidy, if you ask me - at least so far. She did drip a bit on the carpet, though, so I had to take care of that. I also decided to pick up some doggie diapers. Yes, doggie diapers; you read that correctly. They look a little something like this:
Surprisingly enough she has not bothered it at all. And it has been helpful in giving me ideas on how to design and sew doggie clothes. She's doing really well; lots of lounging around and taking it easy while her hormones do their thing.
From what I've been told, heat cycles last about 3 weeks. Of those 3 weeks, the dams only bleed during the first week or so. Heat cycles occur once every 6 months-ish.
If you have any tips about tending to a female in heat, please send them my way.