i'd like to start by saying that i am not a breastfeeding mother, nor will i ever be (i am a father). i am not a professional or school educated dietitian, and these facts may make me the least qualified person to be posting in this topic. i started reading some of the posts, but lack the energy to read all seven pages of replies. if i sound like an idiot, if you think i'm crazy, or if anyone disagrees, this is not the thread to debate, please pass over this reply... i merely wish to offer my opinion. i apologize if i repeat something i did not read.
i interpret there being two parts of your original post:
as far as your concern about producing enough milk for your child, a quick google search of "what foods increase breastmilk production", will bring up plenty of articles relating to this. these foods have nothing to do with you gaining (or losing) weight, just that they help increase milk production. whatever dietary course you choose, it may be prudent to include some of these food items in your menu.
as far as you gaining weight, i would be wary of consuming large amounts of foods that are so high in fat (like recommended by some)... keeping in mind there are fats that are "good", and fats that are "not so good". consuming large amounts of saturated fats (like found in dairy and animal products) can have negative effects on your health, even if taken with the interest of gaining weight. unsaturated fats would be a better option, but keep in mind that there are healthy limits to the amounts of each you consume. eating fats, may not be the best way to "get fat", especially if you lounge around inactive (in an effort to not burn the fats you're consuming). i feel, in the interest of gaining healthy weight, activity is better than lounging, since gaining muscle mass is better than gaining fat mass... this does not mean you need to pursue bodybuilding activities. if food / nutrient absorption is a problem, an active lifestyle would cause you to crave and consume even more food, increasing your chances of getting what you need nutrutionally.
excessive calorie consumption, whether you are active or inactive, will cause unused calories to be stored as fat. this is why people who are trying to lose weight, and are on a low fat diet, may not lose weight, because their calorie consumption exceeds their body's needs. this explains why sometimes, a person can gain weight on a low fat diet... too many calories.
if you, and your doctor, have established how many calories your body needs on a daily basis (whatever your metabolism rate is), then consume more calories than you need in your diet, and include those foods on the "increasing breastmilk production" lists you can find online in your menu. if eating large amounts of foods makes you feel ill, then choose foods that are highest in calories, you will need to eat less of these, therefore the amount of foods you eat will be less, with the same caloric effect.
if your current diet plan (whether raw, or cooked) doesn't provide you with what you need to maintain a healthy weight, you should reconsider your diet. tailor a menu that meets your personal needs, and go with that. if the foods on the breastmilk production list are not part of your personal diet plan, you should remember that caring for your child takes priority over everything else, even your desire to participate in a particular diet style... modify your diet to allow your child, and yourself, to be healthy. when your child is weened, and no longer dependant on you for food "production", you can try a different diet to satisfy you.
if, for your own immediate needs, find you should cleanse, detoxify, or deparasite, then produce as much milk as you can prior, pump it, and store it, for your child to use while you go through this process.
good luck, and best of health to both mother, and child.