When I use pre-made objects like stickers on my cards, I also think that there should be something that I should make or do to the card to personalize it further.
It looks like you've already gotten a lot of positive responses to your card. I liked the suggestion to stamp the background paper but it might be too late for that since you've probably already pasted the stickers onto the page.
One thing you might consider doing is adding some text to the front of the card in addition to what you already have inside. If this were my card, I might add some mounted text blocks under the squares with words like "caring," "sharing," "togetherness," etc., basically words that remind you of the person the card was made for.
Hope this was helpful. Your card does look pretty good already.
-j