After the last time we had protected sex, she immediately turned her back on me afterwards because I refused to try without the condom. She angrily said to me that I should not be afraid and that she wants to feel me inside her.

Personally I would only start going raw on a girl if I'd trust her enough (as in: being ok with her having the keys of my apartment, my credit card number or the code of my cellphone). Then we'd both take STD tests, and if clear, swear not to go raw on anybody else, and keep taking STD tests every 6 months or so.
And if for whatever reason I find myself with a girl pregnant (say condom breaks) and unwilling to abort, I would take ZERO responsibility with the child. If she chooses to keep the child, this is her responsibility alone.

That's my standards, now back to your case. "difficult to get pregnant at the first attempt?" Bullshit, likelihood is just the same. Chances of getting pregnant is there, yeah, but you also have various forms of birth control that she can set up inside her vagina, or by taking pills. Talk to her about it. Ask her how she'd react if she does get pregnant: would she keep the baby? Would she have abortion?

About STDs, if you are in an exclusive relationship, both of you should take a STD test before going raw. And to answer your question: doing it raw feels awesome.

One last thought: THAT is called emotional blackmail, and I would never stay anywhere near a person who would do that.

In short: if STDs is your concern, take a test and evaluate how much you can trust your partner to protect herself (and therefore you too) from STDs. If pregnancy is your concern, ask her to get birth control. And bottom line: you SHOULD NEVER let a girl have you do something you don't want to do.

Quite certain the legal system would see different and make your stupid ass pay child support

I don't want the risks of picking up STDs or for her to get pregnant. We are both not ready for children.

She described the experience like the sensation of receiving a blowjob without the condom. After one second of penetrating, I can withdraw and cum over her tummy. Surely some cum can leak out before the ejaculation. I believe, this will be enough to get her pregnant.

She said it will be difficult to get pregnant at the first attempt and she is not keen on the idea of continuing to practice safe sex. I used latex-free condom as this is what she preferred in the first place.

After the last time we had protected sex, she immediately turned her back on me afterwards because I refused to try without the condom. She angrily said to me that I should not be afraid and that she wants to feel me inside her.

I can't believe that my girlfriend is suggesting this. I don't know what to do. I feel like that she may be trying to trap me into a long term relationship if we have children. I really don't know what her game is. Is there a difference in what a lady feels during protected or unprotected sex?