I took Tai Chi for a number of years. I'm sure you will find it rewarding. Don't let the first few classes discourage you. Tai Chi is more about co-ordination and control than force. Like anything it takes practice. I found a lot of students became frustrated because their moves weren't perfect the first time out or they became directionally lost (for lack of a better term) during a movement. Each time you see the instructor perform the move you learn something new. Repetition is key. Have fun Michelle !
I think the last statement sums it up for me. Have fun Michelle! The other thing to make sure you don't get caught in the trap of doing is comparing yourself to anyone else in the class.
As your teacher should tell you, perform to what is comfortable with your body. Tai Chi is about understanding your body and each of us are individuals.
I also think it's a great thing you're doing for your son! If there's anything we can help here, please let us know. Take your time finding the right school, one that is willing to work with you and that you feel in comfort with the teacher. Make sure they understand the situation too, so they know how to treat your son. There's a few articles up on the site to help find schools: BellaOnline ALERT: Raw URLs are not allowed in these forums for security reasons. Please use UBB code. If you don't know how to do UBB code just post here for help - we will help out!
You were doing Tai chi and your body hurt? Hm. You may be tensing too much. I use to dance too and the two actually should compliment one another in terms of movement. Don't stop, but definitely pay attention to your body, you may not be moving as "oppositely" as you think you are.
One of the unique things about Tai Chi is that it is very much a statement of what our bodies are and each person's mechanics are slightly different.