It is never too late to attend college, so don't let your age stop you from working towards the career that you desire! I do suggest however, that you do some research to find out the requirements for becoming a middle school teacher in the area that you live in. The requirements can differ between regions, educational boards, and even specific schools, so I would suggest that you do your research accordingly so that you can attend the correct college program and receive the training needed to become a middle school teacher.
Keep in mind that 23 is still a young age, and there are teachers of all ages. So definitely consider attending college and fulfilling all the requirements to becoming a middle school teacher.
Hope this helped and good luck!