Hi there, little sister! I looked at your profile and yikes, I'm twice your age!
I appreciate the openness in your introduction here. And yes, I smiled at the way you get emotional when people talk about Jesus around you. What a wonderful thing- it shows how soft-hearted you are toward Him. That's a much better way to be than hard-hearted and stiff-necked.
The tears are embarrassing, yes. Many's the time I've tried biting my tongue or focussing on one spot on the wall in church to keep from crying, but the tears still came. Just remember how many of God's servants cried through the pages of scripture.
The intense emotion will likely subside as you grow in Him, and come through this painful time regarding your grandmother. You'll eventually get a grip, as it were.
Don't squash your emotions or squelch your tears because of the embarrassment though. Keep tissues handy, cry to Him and before Him and let Him comfort you. (If you can go off alone with Him, great, but I know that's not always possible. My mantra was always 'I cry alone' until the Lord added 'unless you don't.')
Psalm 56:8 (KJV) says He collects our tears in His bottle. I've always thought for some of us, it may be a bottle the size of a 45 gallon drum.
The way you've described it, it seems you cry when He's working on your heart, and that's between you and Him and no one else. (Most believers, especially in church; should be sensitive to that, but again, I know some aren't.)
In a way, it sounds like you're where I want to be: one of my personal requests on my long term prayer list is that the Lord would "soften my heart, even though it'll mean an abundance of tears and I hate crying...."
He understands your tears. The hosts of Heaven may have cried some of their own in their joy at your return.
Stay soft, for His sake.