Finally, another thing to keep in mind is that instructors, even those who have been practicing all of their lives, aren’t perfect. They have off days. They have off weeks. Your best friend my love the same one that made you feel uncomfortable. For some people they get lucky and love the first yoga class and instructor they come to. For others it’s a harder process and may take work.
Yoga was originally conceived to help monks achieve an inner peace and to get their bodies ready for long meditations. It was taught by a guru to one student at a time. Today classes can contain as many as 20 people. You have to be the judge of whether that feels right for you. Trust your instincts, ask questions and then trust your body. Now go forth and find your teacher.