Keep with it, I was in the same boat. Take a step back, look at how you are teaching and think "what did I like/no like about how some instructors have taught me in the past". Your greatest tool is other instructors you either admire or hate. You learn how to do it right from those you like, and avoid being like those you didnt. Learning to properly teach was very hard for me. But well, well worth it. If you want to become less shy, learn to teach. You will become more social for sure. Once you get it you wont forget it. And your mom saying you arent a good teacher is very funny/ironic coming FROM a teacher. Way to discourage someone who is trying to learn...(laws of learning anyone?). First rule of flight instruction, dont get mad or criticize at your students. (constructive criticism is good though, if done right). What she should have said is "thats pretty good, however this is how you could improve that...". She may be a certified teacher but that doesn't mean she is good either. How many of us have had horrible flight instructors or teachers in HS and/or college? Learn from them.
What books have you read so far? The laws of learning are very important to understand how people need to learn. You cant just blurt out facts, draw crap on a white board and expect comprehension.(although, pilot mills seem to die trying) I wish when I was in CFI training someone offered me a bit more than "I would say it like this" or "no, thats too complicated, make it more simple" type suggestions. Message me if you need some help, I got time on my hands! Slow corp. flying and instructing is a little slower in the winter with 35 inches of snow in 1.5 days