It’s common, though I experienced the opposite. Some say that they start craving very bland food, and I know for me, I ate the same dinner for months after my last one, which was honey glazed squash (very caramelized is how I liked it) with plain pork and plain millet. The millet was a bad idea to keep up with for so long, but I’m guessing I craved it because it was sweet.
It seems women who loose their appetite see it return at least by the second month, so I wouldn’t be too worried, but make sure you watch out for signs of calorie deficiency, like shakiness. Snacking throughout the day is probably a good idea.
I think it’s a normal hormonal response to adjusting to having baby outside of the body. But if you lost a lot of blood, it can be due to low iron stores.