Robbo, I'm most certainly not claiming that my answer is utterly correct and not capable of improvement...however...
a) 'vita' is a feminine singular noun and must be qualified by a feminine singular adjective form. 'Meus' is a masculine singular adjective form, so 'meus vita' is a non-starter.
b) the preposition, 'per' takes the accusative case of the words it is associated with, so you would have to write, 'per tuam scientiam'.
c) the statement given, 'My life (is/has been) enlightened by your knowledge' is passive, so - as a motto - I thought it might be better in the active form. That is, 'Your knowledge has enlightened my life."
d) Word-order is important in Latin and quite different from word-order in English. In other words, translations to and fro are very rarely indeed 'direct'!
My advice to you, Meggie, is to take these and any other translations you might be offered to a Latin teacher at your local secondary school or even to an older Catholic priest. They will be able either to correct what you've been offered or simply tell you an altogether better way of translating your message. Good luck.