Place the chicken breasts in the instapot with 1/2 cup of water. If thawed chicken, pressure cook on high for 12 minutes. If frozen chicken, pressure cook on high for 20 minutes. Let stand for 5 minutes and then release pressure. Take chicken out of the instapot and shred. Dump the leftover juices out and wipe out any extra chicken bits in the instapot. Place shredded chicken back in the instapot with all of the ingredients except the fresh thyme. You may need to add in some water if the chicken stock isn’t enough liquid. Remember the noodles will plump up with cooking, the liquid needs to be just to the top of the ingredients. Pressure cook again on high for 5 minutes. Let stand for another 5 minutes then release the pressure. Add in the fresh thyme if using and serve immediately. If making this recipe in advance, do everything except adding in the noodles and thyme (even if you are using dried thyme). Then package up for consumption later. When going to eat the already prepared soup, add in the noodles and thyme and cook until thoroughly heated through and the noodles are soft.