Blood Donating.

I don't even know how I want to approach this. Since last year, I've wanted to donate blood to the Red Cross. I've been denied 3 times. Why? Because at 18 years old, 5'2 1/2, I weigh only 106 pounds. Now, I could try to gain weight, but I have the fastest metabolism in my grade. The minimum weight is 110 for the Red Cross. This is honestly a topic that upsets me because I really want to do this BUT I CAN'T FUCKING HELP THAT MY BODY BURNs CALORIES FASTER THEN ANYTHING. It's not my fault...what can I do? The people who are taking sign ups are giving me shit because they say I am taking away blood by reserving a slot for people who actually CAN donate blood where I have to get checked and will possibly be told no. I'm tired of being rejected...and I don't want to hear, "You can donate financially!" Because I work a part time job, and I'm saving for a car. Blood is regenerative, money takes work. God this upsets me.