The stress of exams/deadlines tend to be a trigger for my anxiety. Procrastination sometimes saves me from that anxiety, but I have to deal with a much higher level of anxiety when I have to rush to meet the deadline. Breaking the task up into small, manageable pieces makes it feel less overwhelming and makes me feel like I've accomplished something, which helps build momentum!
maybe because you are worried of ruining everything, so by procrastination you feel better and more calm now that you don't have to face your tasks. It happens to me a lot, when I am scared about an upcoming exam or assignment, I keep on procrastinating it out of fear until I cant procrastinate anymore
Procrastination can get worse before exams/deadlines because we can see these moments looming before us and we are trying desperately to avoid them because they are either boring, uncomfortable or stressful to deal with. Putting the work we have to do out of our minds with procrastination can provide temporary relief, like a band-aid on a wound.
Different people handle deadlines (and procrastination) differently. For some, getting closer to a due date results in a "fight" reaction, a drive to work harder and get it done. For others a "fear" reaction or giving into the assumption they wont make it anyway. Its important to not let fears and doubts rule your behaviour. From your question I would say you have already recognised the problem. The next step is to address it. Fight past your fears and doubts, focus on the task at hand. Break it down into smaller more manageable tasks and take them on one at a time.
This may occur because the work load may be great and seem increasingly difficult so the first thought that comes to mind is maybe later and this may be very hard to come out of it helps to dedecate time to this tasks and create a suitable environment for this task