is there anything you should or shoudn't eat while BF?
is there a diet to follow while breast feeding?
It's wise to eat a decent diet while breastfeeding but there are no specific diets or foods you should or shouldn't eat. The main thing is to watch your baby for allergic reaction. For example: some moms find that eating dairy or drinking coffee causes their babies to have intestinal upset so avoiding these food for these moms while breastfeeding is a good idea.
This artilce explains more-
https://www.kellymom.com/nutrition/mom/mom-diet.html
How does a mother's diet affect her milk?
By Kelly Bonyata, IBCLC
Do I need to maintain a perfect diet while breastfeeding?
What IS needed for maintaining an ample supply of milk?
How does mom's nutrient intake affect breastfeeding?
Are there any foods that nursing mothers should avoid?
Additional information
Do I need to maintain a perfect diet while breastfeeding?
The short answer to this question is NO you do not need to maintain a perfect diet in order to provide quality milk for your baby. In fact, research tells us that the quality of a mothers diet has little influence on her milk. Nature is very forgiving mothers milk is designed to provide for and protect baby even in times of hardship and famine. A poor diet is more likely to affect the mother than her breastfed baby.
It's common to hear women say that they want to wean (or not breastfeed at all) because they miss drinking coffee, or want to have an occasional glass of wine, or don't like worrying constantly about everything they eat. Guess what? You can drink caffeinated beverages (in moderation), have an occasional drink, eat what you want and still provide your baby with the absolute best nutrition and immunological protection - mother's own milk.
According to Katherine A. Dettwyler, Ph.D., breastfeeding researcher and anthropologist, women throughout the world make ample amounts of quality milk while eating diets composed almost entirely of rice (or millet or sorghum) with a tiny amount of vegetables and occasional meat.
Are healthy eating habits recommended for mom? Absolutely! You will be healthier and feel better if you eat well. It is best for anyone to eat a variety of foods, in close to their naturally-occurring state, but this is not necessary for providing quality milk or for maintaining milk supply. Although it is certainly not recommended, a breastfeeding mother could live on a diet of junk food mom would not thrive on that diet, but her milk would still meet her baby's needs.
What IS needed for maintaining an ample supply of milk?
The main thing needed to maintain an ample milk supply is simple --
The more often and effectively your baby nurses, the more milk you will have.
Occasionally, a mother's calorie or fluid intake can affect milk production:
Calories: In general, you should simply listen to your body and eat to appetite - this is usually all you need to do to get the calories you need. Counting calories is rarely necessary unless you are having problems maintaining a healthy weight. Excessive dieting can reduce milk supply, but sensible dieting is generally not a problem.
Liquids: It is not necessary to force fluids; drinking to satisfy thirst is sufficient for most mothers. Unless you are severely dehydrated, drinking extra fluids is not beneficial, may cause discomfort, and does not increase milk supply. It is not necessary to drink only water - our bodies can utilize the water from any fluid.
The main message on calories and fluids -- Eat when hungry & drink when thirsty.
See Do nursing mothers need extra calories or fluids? and How does milk production work? for more information.
How does my nutrient intake affect breastfeeding?
Vitamin/mineral supplements (prenatal or otherwise) are not considered necessary if you eat a reasonably well balanced diet. See Vitamins (& other supplements) for Nursing Moms for more information.
Your fat intake does not affect the amount of fat in your milk, but can affect the kinds of fats (balance of "good" vs. "bad" fats) in your milk to some extent. See What affects the amount of fat or calories in mom's milk? for more information.
Are there any foods that I should avoid while Im breastfeeding?
There are NO foods that you should avoid simply because you are breastfeeding. It is generally recommended that a nursing mother eat whatever she likes, whenever she likes, in the amounts that she likes and continue to do this unless baby has an obvious reaction to a particular food.
It's suggested that everyone, particularly pregnant and nursing mothers, avoid eating certain types of fish that are typically high in mercury.
It is a good idea to restrict caffeine and alcohol to a certain extent, but it is rarely necessary to eliminate them.
Some food proteins (such as cow's milk protein or peanut protein) do pass into mother's milk. If there is a history of food allergies in your family, you may wish to limit or eliminate the allergens common in your family.
Any baby might react to a particular food (although this is not very common). If baby has an obvious reaction every time you eat a certain food, it may be helpful to eliminate that food from your diet. For more information, see Dairy and other Food Sensitivities in Breastfed Babies.
Making women think that they must maintain perfect diets in order to have thriving breastfed babies is an unnecessary obstacle to breastfeeding.
I know that can be hard work and I'm so sorry your last experience was so difficult. The good news is your last experience has no correlation on whether or not you will be able to successfully breastfeed this time. Try to stay positive and relax. You can do it! 
