Avinash,
You aren't practicing birth control by pulling out before your sperm comes out.... you are just plane gambling.
Sooner or later, you loose. We have a name for people who do what you are attempting.... "Parents".
You have got to use protection EVERY time you have sex. If not, it's only a matter of time before she becomes pregnant.
Some believe that pre-cum (that clear fluid that oozes or weeps from the head of the penis during high arousal) can contain sperm cells. It only takes one.
As for the blood, it's possible that you worked some of her blood up your urethra, if I understand what you're saying.
it's also possible that you simply had her blood on you, and that it ran down your penis or had started to clot and you didn't notice it.
I have to take issue with Brainwrek's assertion that "if your sperm is really white an dthick that means your sperm is really strong."
No, all that means is that you have a lot of white in your semen and perhaps have not had sex for a while, so that it might be more thick. Or that you're a bit dehydrated. It doesn't mean "Your sperm is really strong."
However, his final statment is very correct...."Despite 'pulling out' your partner can still get knocked up (pregnant)." Use protection.