Advice for making/keeping shredded chicken moist? My dietician ordered that I eat chicken. I found that to eat the portion I'm supposed to eat (10oz), it's easier to shred the chicken and take 10oz of shredded chicken, rather than try to find 10oz breasts. I am trying to meal prep this chicken over the week. 

The way I currently cook my shredded chicken is I take raw chicken breasts, throw them in a steamer basket, put the steamer basket in the instant pot (pressure cooker), throw in about a cup of chicken broth and 1/2 cup of pineapple juice, and then pressure cook for 15 minutes with a 5 minute natural pressure release. I then pull out the breasts and shred the chicken breasts. I then store the shredded chicken in the fridge.

The problem is that the shredded chicken is terribly dry. Whenever I reheat the chicken it tastes like I am eating chalk (in terms of texture). This makes it impossible to stick to my diet. 

Can someone give me advice on how to cook shredded chicken and maintain moisture for several days (at least 3)? I am not a good cook and I don't know if the problem lies in the cooking, the storage, or the reheating.

Thanks
The first issue I see is that you are over cooking your chicken breast.  20 minutes in a pressure cooker is really over doing it.  Even a little over cooking dries chicken breast.  Chicken breast needs to be cooked more precisely.  A pressure cooker is not the correct tool for the job.  So you first need to correct your initial cooking.  You should get a good thermometer, ensure it is calibrated, and cook your chicken breast to an internal temperature of 160F (71C).  You can remove the chicken breast from the cooking surface when it is a couple of degrees below that.  Let it rest 10 to 15 minutes, and the heat will carry over and you will reach the final target temperature.  This will allow you to begin with moist chicken.