Thank you doesn't seem enough

What do you say to someone when "thank you" just doesn't seem to say enough? Is there another phrase that means more than "thank you" or "I appreciate you"?

Yesterday, Gavin went to Miss Andrea's for the last time. Next week, he starts his week of summer camp at his new preschool (work starts again for me) followed by Pre-K 3 the week after. Gavin has been going to Miss Andrea's for 2 years now. He loves her and talks about her all the time. Andrea was so patient with him and just knew him. She knew how to handle his difficulties with transitions, what he was really trying to do when he told her "my belly hurts", and how to convince him he didn't really need to take a nap to handle a new situation. Andrea knew how to help him do messy paint projects by telling him she would immediately wipe off his hand/foot when she was done. She loved on him and loved him like he was her own. What are we going to do without that? Who is going to snuggle him until he has adjusted to the setting? Am I going to get a phone call every day telling me to put my kid to bed earlier because he is always saying he wants to sleep or to come get him because he has a belly ache? Change is hard. I don't like change. Gavin really doesn't like change. Change is HARD. Did I say that already?

So, Andrea, thank you. Thank you for being you and for caring for my child. Thank you for waking up each day ready (with the help of coffee) to help shape my child (and other children) and help him grow. Thank you for your love and patience. Thank you for always telling me about how his day was and what funny things he did while I was at work. Thank you for all the wonderful gifts you helped him make for Carl and me. Thank you for laughing behind his back when he was acting a fool as soon as I arrived to pick him up (because, we all know he only acted that way once I arrived). Thank you for knowing how to help him regulate when he was overly emotional at your house over something like having to take his shoes off. You are amazing. It takes a special person to care for little ones and I'm so glad we found you. From the bottom of our hearts, thank you, we appreciate you, and you will be terribly missed!

We love you!