These exams are coming whether you are ready for them or not. Worrying isn't going to stop that, so you might as well stop worrying and start doing something to help yourself.
Are you revising all the time?
You may think this will help you but it probably won't. You need to de-stress and take time to rest. Burn out can be worse than not revising at all.
Have you not revised at all?
We cannot change the past so don't re-play your procrastination in your head. The best solution is to do some revision now. Some revision is better than no revision.
Procrastination:
Are you finding it hard to get started? Do you find other things to do with your time even though you know you should be revising. Here is a great description about procrastination with some solutions:
https://waitbutwhy.com/2013/10/why-procrastinators-procrastinate.html
And here it is in video form:
https://www.ted.com/talks/tim_urban_inside_the_mind_of_a_master_procrastinator?language=en
Getting Started:
Here are some tips on getting started:
https://www.lifehack.org/articles/featured/11-practical-ways-to-stop-procrastination.html
It is also a good idea to reward yourself. Give yourself half an hour gaming time for each hour of revision. Allow yourself one episode of Neighbours for completing a mock paper. Getting started is hard so help yourself feel proud when you get some revision done.
Starting to Stress?:
Stress is our body responding to pressure. If you are starting to feel stress or anxiety it is time to take action. Here the NHS explains what stress is and the signs and symptoms:
https://www.nhs.uk/conditions/stress-anxiety-depression/understanding-stress/
A little amount of pressure is OK as it could drive you to action. A lot of pressure is not OK and can drive you to burn out or break down. If you are starting to feel pressure, take a break. Get some perspective. Breath slowly and think about how you can slow things down to stop your heart from racing.
Here are some relaxing games you can try to help you calm down:
https://www.lifehack.org/articles/lifestyle/10-relaxing-online-games-help-chill-you-out.html
The revision will be ready for you when you are ready to come back to it. Your health is more important than the exams.
Talk to family, friends and your teachers if you start to feel overwhelmed.
Solutions:
Worrying is never going to solve anything. You need practical solutions. Stop thinking in barriers and problems and start thinking in solutions:
I haven't started revision = When can I start revision?
I don't know what I'm doing = How can I find out what to do?
I have so much to do = What would be best to prioritise?
People are too busy to help me = Where can I find help or resources online or at school?
You can do this.
https://www.childline.org.uk/info-advice/school-college-and-work/school-college/exam-stress/