Hi there.
You can't know your actual score now.
The final cut off list will be declared by NTA after the April session of the JEE mains examination.

As for now, your probable rank can be calculated. 

Now, A total of 874469 candidates wrote the exam. Since the percentile is calculated from a scale ranging from 100 to 0 for each session of examinees, the formula applies the total number of students in the January session which is 874469 /100 multiplied by the percentage of people who are ahead of you to arrive at the rank.

Therefore, the formula to calculate the JEE Main 2019 rank for January 2019 is

JEE Main 2019 rank (probable) = (100-56.93  ) X 874469 /100 = 376634 (approximately)

This rank may inflate or deflate depending on the total number of candidates who write the examination. in the April session. 

You could take a probable calculation and see where you stand. This means that you take a hypothetical number of the candidates who will appear in April. If you go by past trends, the figures are somewhat between 11 lakhs to 12 lakhs. Using this as a basis, use the NTA score and see which JEE Main rank you will get. 

Using the same formula,

If NTA percentile score is 56.93, JEE Main rank will be (100-56.93) X 1200000/100 = 516840

Now, using this estimated calculation, you can check previous year cut off trends and think of an idea of the probable colleges.

Check the following links for previous year trends in cut off :

https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-cutoff/amp

For college predictor of JEE mains, check the link below:

https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-college-predictor/amp

Hope this helps.
Good luck!