ESH. This isn't a game of make-believe where sometimes asking someone to marry you "counts" and sometimes it doesn't. It always counts. And then his bit of "taking it back" (again, what is this, a game of tag? No takesies-backsies!), taking his blankie and leaving... You're both treating this childishly.
If you wanna follow through with marrying him, then sincerely apologize and say that you really do want to marry him and want to celebrate fancy and make that the "she said yes" record-making moment. I know that "going out" to celebrate may or may not be in the cards, so if you can't, just get some champagne and get out the champagne flutes and get a fancy treat (caviar on mini-toast, chocolate-covered strawberries, anything...!), dress up fancy, light some candles, put on some classy dinner music and raise a toast to your engagement.
But tbh, if you do follow through with this engagement and marriage, work on your communication. You both sound really immature.