If you don’t have a thermometer, there is a very low tech way to educate your senses to determine a steak’s doneness. Place the thumb and index finger of your non-dominant hand (left if you are right handed) together lightly. You want to just touch them together with no pressure. Then, feel the large muscle at the base of your thumb. Press the muscle with your dominant hand and really pay attention to how springy it feels. What you are feeling is the way a rare steak will feel if you press on it. Move your thumb to touch the middle finger - same instruction, don’t press, just touch thumb and middle finger together. Now feel that same large muscle at the base of your thumb with the same level of investigation. That is how a medium rare steak feels. Now move your thumb to the ring finger - same drill - feel that large muscle and you have the feel of a medium well steak. Lastly, put together your thumb and your pinky. Touch the thumb muscle again and you have a good read on how a well done steak will feel. So - press that steak. Be quick and don’t burn your fingers! This method isn’t perfect but it is a start to learning how to cook with sensory awareness.