Yes, you are feeding way too much for that many shrimp. For 14 shrimp I would feed a piece about this big __ every other day or every third day. Plus, if the shrimp are not used to eating commercial foods they won't be as likely to come to them. Some shrimp are just happier eating biofilm and don't want much in the way of pellets or wafers. I've had some that wouldn't touch a thing I put in the tank and were content to eat off cholla logs and moss. It's no big deal really. But yes, you are overfeeding and are going to come into a large fauna problem (critters you don't want rather) if you don't cut back.