Do you think this is a good sonnet?

For my English class i have to write a Shakespearean sonnet. It has to be in iambic pentameter and the couplet has to summarize the entire sonnet while bringing a new light to it. I'm not concerned with the iambic pentameter too much, but I would like another opinion other than my mom's :)

On snowy days you are the ray of light

That pierces through the grey blanket of doom

To carry me out from the endless night,

And eliminate my aura of gloom.

On days when God’s giving you’ll come to me

To save my ship from the sea of sorrows;

My beacon of hope when I cannot see,

You guide me to shores of our tomorrows.

However in truth you’re a fleeting being

That at any moment can disappear

Just by closing the curtain’s heartless string

And in such instance I cannot feel you near

Though no matter what your light will still shine

Deep in my heart, since it knows that you’re mine.