Grammer Ma'am

So, I'm working on my master's degree project. And I am, apparently, horrible at formal writing and grammar. I mix up their and there, here and here. I talk about "that" when I should be talking about "who". I end sentences with prepositions. I use contractions. I don't spell out words completely: vocabulary (vocab) and laboratory (lab). My sentences can be complex and confusing.

My master's degree advisor's PhD is in biology, not grammar, he keeps telling me.
And to top the hole ( :0) mess off, I keep wanting to spell grammar -grammer!

Thank the Lord for the red/green squiggly line or I'd be hopeless.