I just turned 32, so I wish I was 21 again. I literally did nothing for my 21 birthday. But, the other day, I spent it all and four more days with my BF. We showered together, then had sex, then went out, had sex on the side of someone's house, then walked around, then went back to his place, his roommate wanted to get drunk, we didn't, she went to bed, I gave him a BJ and he came in my mouth lol but he wants me to swallow from now on as he wants it inside me. heheheheheheh Jeez I'm gross but I love that cause when he does, I know he likes me. You can't orgasm unless there is attraction, so it made me feel great. So it was a great birthday. I think the most important part of a birthday is just spending it with the man you love.
But really, August 11 is a long way off. I would focus on the here and now rather than something that is two months off. Don't waste the day thinking about the 'morrow.