At the moment there is no way to check the balance other than doing a new transfer. But you will be notified in a comment when your balance is running low.
You will shortly be able to do this via Discord, where you can query a Dustsweeper bot for your balance and other stats.
I noticed you sent me 2 SBD, can I send it back so you can give out the gifts yourself?
I am a man with only two eyes. I can only see so many ways to use it. It is my gift to you, to use however you see fit. Keep it if you want, you deserve it. Time is so valuable, and you have spent yours helping(and enabling others to help) so many people here. You do truthfully deserve it, and so much more. Thank you my dear friend. As always I send yous all of my love. And offer all my encouragement and support when I can. I hope you have a wonderful day.