Everyone must learn at their own pace

There is no competition in Tai Chi & Qigong classes. 
It can be a natural reaction to compare oneself to others in a group, but this is not at all helpful.

A more productive approach is to focus on what you are learning and you are getting from your own practice.
Unlike other forms of exercise, where overtraining can cause injuries,
Tai Chi & Qigong give you more benefit the more you practice.

It's very much like learning to play a musical instrument. The more you practice, the better your progress

Learning Tai Chi principles can also be like doing a jigsaw puzzle.......
parts of it gradually start to make sense and then, over time, the bigger picture begins to become clearer.

Sadly, many beginners give up because they feel they aren't making progress quickly enough.
Learning a Tai Chi form is not a race to learn a sequence of moves.....it is a journey of discovery.
The most positive way to approach your practice is to focus on what you remember,
and not become frustrated by what you can't......... one day you will !