Well done, my friend. Also, congratulations on going for a level 3 lesson and doing a good job
Ok, Alex has made some important points which I would also agree with. Remember that vibrato is like string bending. You have to return the string back to its original pitch between oscillations or it will sound out of tune.
The other thing I'd suggest is to do your vibrato motion downwards, not upwards. If you do it upwards, there is less control and it's also inconvenient to do it like that on the A string and low E because there's not enough fretboard to go wider. The only time that upwards vibrato is useful is on the B and high E string because that's the logical option as there's not enough fretboard to do it in a downwards motion. So, to recap, try this:
E, A, D, G Strings = Downwards B, E strings = Upwards.