Thanks for the extra info. I think there are a few things going on:
1) You had a lot of restricting in different ways, and I can only imagine some nutritional deficiencies.
2)Being vegan in and of itself can lead to some deficiencies longterm (such as zinc, B12, iron, protein, etc) but dieting on top of that even more so.
3) Pregnancy and breast feeding pull a lot of nutrients from the body (and calories). Also now if you are weaning your son, you are not discharging some calories that he was taking in. There are also some hormonal things going on probably.
4) Your metabolism must have been very low if you gained weight on a green smoothie diet.
5) A low-carb diet makes you even more susceptible to weight gain when you reintroduce carbs.
(You didn’t mention medications, so I assume that’s not a factor, but if you are on any meds you should make sure they don’t cause weight gain, because that + RRARF will cause massive gain every time.)
So you have a lot going on! Which makes sense that you gained weight so fast, and a good amount of it probably is water weight. Your body has been deprived for a long time and it needs to heal now. The bad news is, some weight gain is probably inevitable, unfortunately. I think the best thing to do is make sure you are really nourishing your body. Which would mean: eating 3 balanced and healthy meals per day (with protein, carbs and some fat – such as toast with scrambled eggs, or a turkey and cheese sandwich with fruit and a yogurt, or roasted chicken with boiled potatoes and a little butter and roasted veggies and fruit for dessert. Basically like what your grandma would have considered a “square”.) and 1-2 small snacks per day (like a cheese stick and a few crackers) on a very regular schedule (meals at roughly same time every day, no skipped meals, similar amounts each day) to show your body it is no longer starving. Personally I think taking prenatal vitamins might be a good idea, or a good multi, since you are probably very depleted.
Matt may disagree, but I wouldn’t recommend junk food, except on occasion. Since you were vegan for so long, I suspect you have a high need for protein and meat, but if you were low-carb for awhile your body may have gotten its fill of meat. But if you are craving meat, load up on it at meals. What were you eating in TX and AR at the BBQs? Lots of meat? If that was during the Green Smoothie phase that makes sense as your body was totally protein deprived.
I know a lot of people start just eating whatever on RRARF, but that is a good way to gain weight fast. Putting some regimentation, balance and moderation in will probably help, and it will make your body happier. It likes routine.
I would not recommend exercising much right now, except for things like walking, stretching, light yoga. Things that make you feel good. When you come out of starvation mode, you can add in more.
It sounds like you are very stressed out and have a lot on your shoulders right now, so anything you can do to make yourself feel better and sleep better would be a good thing.
I hope this helps. Please let me know how it goes.