The cylinder number refers to the astigmatism, the sphere number refers to short refers to standard short sight.
The CAA limits are:
cylinder, not any more than -2, ie -3 is too much.
sphere, not any more than -5, ie - 6 is too much.
However, the 2 numbers added together must not be greater than -5.
ie, sphere -3, cylinder -2 is ok, sphere -5, cylinder 0 is ok, but cylinder -2, sphere -4 is not.
It would appear in your case that your cylinder numbers fall outside the limits, which might at first glance proclude you from passing the medical.
HOWEVER, do not be put off by this. I had a similar problem, in that my prescription was slightly outside the limits, but I gained a class 1 medical through something the CAA call a "deviation", which is a special loophole in place to allow people who fail to meet the requirements by some minor technicality to get a class 1, provided they are fit in all other areas.
I reckon there could be a good chance of u getting the same, particularly as your sphere number is well within the limits. You are however quite young, so your eyes might not have settled down properly yet, which may be an issue. In fact you appear to be 17, I think you need to be 18 to get a class 1.
The guy you need to speak to is Adrian Chorley in the CAA medical department. He is their eye man, so to speak, and also a very nice bloke sympathetic to a situation such as yours.
Finally, I would advise you to try and get the class one asap, as your eyes might get worse over the next few years, worsening your chances.
Good luck!