I believe that the radius of your large circle (the one containing the other 11 smaller circles) should be about 11.554648868472 mm

I got it as follows:

the circumference of the large circle is equivalent to the diameters of the 11 smaller circles, or 11 * 3.3 mm = 36.3 mm

the formula for circumference = (2 * pi * r) or (d * pi)

plugging in the numbers:

36.3 mm = d * pi

36.3 mm = d * 3.14...

d = 36.3 mm / 3.14...

d = 11.554648868472 mm

NOTE: Please note that this calculation will be off slightly, since the circumference of a circle is actually curved, whereas the calculations above use the diameters of the smaller circles which are straight. But it should be pretty close.