We've spoken before. Your diet sounds great. I can't really offer any suggestions on gaining weight. What I believe is that we each have a more or less ideal weight for us to be healthy and to function well. I have weighed the same for years now, almost to the pound. Some people think I'm too skinny or I ought to eat more. I think I'm just fine. You may be at a weight that is right for you. I did notice small bodily fluctuations with cleansing though. For example, as you clean the colon you may start absorbing nutrients better and may need to adjust and to eat more or less quantity.
I will say with regard to the acne. If you were toxin-free, you would not have acne. I'll guess you've been exposed to toxins somehow, maybe food supply or environment, bad air, stress, any number of factors. with regard to the enemas, when people tell me they did "an enema or two" and "did not notice any difference" I believe that they have not done enough. I would suggest a lengthier Colon Cleanse involving a series of colonics and use of a product like "Colosan", or a series of enemas at home. My first cleanse was a 5-week sequence of enemas. It had a particular rhythm and worked very well, as I mentioned. If you would like this protocol I'd be happy to post it for you. You cannot expect results trying something once or twice, especially if your bowel is toxic it's going to need more than a couple to get that gunk out!
Glad to hear you do yoga practices (pranayama) too!