Trying to guess doneness based on look and feel alone can often be a gamble. Using an internal temperature thermometer will help to guarantee your meat is cooked exactly how you like it as well as to ensure food safety.
Keep in mind that meat will continue to cook while it's still hot (up to 5-10°F) once removed from heat. To keep your meat as juicy as possible, let rest for at least 5 minutes (or longer for larger cuts).
Tip: When inserting the thermometer, make sure it is done through the side and reaches the centre, while avoiding any bones or fat.