Carb Nite you go ultra-low carb for 6 of the 7 days of the week. Under 30 g of usable carbs. On the 7th day of the week you go on a six hour binge of high glycemic carbs. When you go low carb for more than this period of time, as you found out, you start to feel like crap. The Carb Nite reignites your fat burning hormones. As an engineer, I am very skeptical of everything and I want scientific proof. I review scientific documents for a living and I can say the amount of research Kiefer (the author of Carb Nite and Carb Backloading) did is astounding. The science is solid.
I think the main problem with your lifestyle is your exercise. You exercise too much and do too much cardio. This is putting a massive amount of stress on your body. Under Carb Nite or Carb Backloading you won't do any steady state cardio. Maybe one HIIT workout which should only be 20 minutes. You will also want to lift heavy. You don't turn into the she-hulk. As a bodybuilder I find it insulting you think getting big is that easy. Check out Julia Ladewski (she's on this website). She is a competitive power-lifter and she doesn't have a massive physique. You don't have to completely annihilate your muscles just a decent stimulus. For questions about a female appropriate workout ask Naomi (the admin), she also lifts heavy.
For more info why your current exercise program is wrong I highly reccomend this article by Kiefer: http://articles.elitefts.com/training-articles/women-running-into-trouble/
I'm finally caught up... I agree here, that I think you're doing too low cal and too much exercise. 60 minutes of this hard yoga, then another 60-90 minutes of weights circuit, then spin 2x a week, then running (possibly) in the evening. I think you've been doing it for so long your body is just way off track. How to reset that (metabolically, hormonally, etc), I'm not really sure.
Regarding the science... yes, Kiefer bases all his stuff on science. And it's right and it works. Or he wouldn't put it out there. That having been said, there are always individual adjustments, needs and concerns. So please don't take the science and throw it out the window. Will you need some tweaks? Most likely based on your situation. And honestly, Kiefer might be the one with most of the answers.
Both books (carb nite and carb backloading) are worth the read. Whether you end up "following it to a T" or not, you need to understand the metabolic and hormonal processes. That will then help you make adjustments further.
Getting lean was not easy for me. I've always been (at 5'2") between 130-140. sure I'm probably a little more muscular that you, but I never could get lean... cut calories, run more, lift more, didn't matter. that is UNTIL I started backloading a year ago. I began to slowly see my abs. It was slow (b/c remember, CBL isn't the best for cutting fat... at least not like Carb Nite) but it did start slowly cutting fat. I was ok with the slow process. After 6ish months, i tweaked it some more... based on the book (that's when the ebook finally came out). Then I tweaked a little more. I felt AMAZING, strength-wise, i wasn't bloated, i had great energy, etc. etc. Then, I began working with Kiefer. And it all took off. And even the pictures in the article that were just put up weren't my leanest days!!! My weight only dropped a couple pounds... and the kicker is that i was doing this to make weight for a powerlifting comp... not to get lean. And the other kicker, I did a whole 2 sessions of HIIT. I typically don't do cardio (other than maybe going for a walk with my kids)... I did 2 HIIT sessions the first week of working with Kiefer and that was it!
Sometimes when we focus on losing weight or even losing fat, the results just don't seem to go as planned. Unless you have someone else doing your training and nutrition. Oftentimes what we see is very different.
I agree that heavier lifting will definitely help... in fact, I am one of the co-founders of the Girls Gone Strong movement that you'll find on face book (www.facebook.com/girlsgonestrong)
. I'd be curious to see pictures of what you looked like when you were "bulky"... again, typically our vision of ourselves is skewed by what we think we see.
Please get the book(s). CBL comes with access to parts of this forum that you otherwise wouldn't have access to. Carb Nite will help you understand that portion as well (although much of it does need to be updated, but it will still help). And finally, if you're still not certain, I would consider getting a consultation.