As expressed by all here, you seem to lack confidence. The only way to improve this is to get plenty of hours behind the wheel. You have 2 months till your next test date so use this time to gain this experience. I have no idea of your age, or if you live at home with access to a vehicle (mum, dad, partner) but in an ideal situation you should go out at every opportunity that arises, including the 5 minute drive down to the local shop to pick something up.
Nothing beats driving experience to build one's confidence. When behind the wheel it is always important to "expect the unexpected" and to continuously read the road ahead (and behind, by use of all 3 mirrors and where necessary your blind spots).
You have no control of how other road users drive or how they react, but having an idea of what actions you would take in certain situations based on what is going on around you will make you a better driver and you will grow in confidence.
As a driving instructor many moons ago in the UK, I would place great importance on my pupils going out to practice in-between lessons, luckily for us at the time in Scotland, Arnold Clark had just started renting out dual-control cars by the hour to the general public (making it far cheaper than paying for an extra driving lesson, my hourly rate at the time was £13, and a dual control car hire was at £6.50), unfortunately I only know of one company doing this in Switzerland, and they are in Lausanne.
As for the driving test itself, 9 out of 10 pupils will never drive at their optimum ability (if taught correctly, you should reach a standard that is not simply to "pass" the test, but be above that so that when your standard drops during the test, you will hopefully still be above the required passing standard. As an aside, as driving was new to all my pupils, they had nothing to compare it to so what I did, and unbeknown to them at the time, was to teach them the Advanced Driving skills I had to learn for my part 2 ADI test, the test results backed this decision)
The fact that you are suddenly confronted by a person you have never met before sitting next to you and not engaging in any conversation (as you would with your driving instructor) can be very off-putting. Also, during the test you may find yourself in a road traffic situation you have never experienced before that will make you sweat (again, expect the unexpected), the idea is to remain calm and if you have constantly read the road ahead and around you, you will be more prepared to react correctly and in a timely manner.
Get out and practice every day if you can, and good luck with your next test!