Why am I sad over this?

[Android-18]

I put mature because in my opinion this can be a sensitive subject, and I'd honestly like it if people don't spam up this topic.

I donated blood today. Why? I don't even know. I keep telling myself it's right, it's a good thing, I might save a life by doing this. The blood drive was at my school, and woman asked my last class of the day if anyone 17 and older would like to sign up. It kind of hit me like a train. I saw the flyers, I knew it was there, and I thought to just walk past it. Only two of us could in my classs, and when I looked uncertain I swore my teacher (whom I admire) give me a disapproving look. So I took some time to think about it.

People would respect me, right? I'd be doing a good deed, I wouldn't be selfish. So I did do it...I gave my blood...and I feel depressed about it. I always used to tell myself I would never give blood, I don't want anyone having my blood in them. I'd laugh at those comercials that said "Blood, it's in you to give." and say "Blood, it's in you to live." and now it's not so funny.

Shouldn't I be proud, happy, mellow? I feel neaseas and down right sad. I don't know what to think, no one helped me decide, I had no support. Maybe I made the wrong choice...I don't know.

Have any of you hit this crossroad before? I just need to talk about it...