How can I get comfortable enough to sleep with someone after only a few dates?

This isn’t a troll or me trying to shame people. Just the opposite. I (19F) have just started to date seriously and I admit I am a little naive and in serious need of advise.

I hear that many people consider 3 dates to be enough to expect to go sleep with someone, assuming they don’t want to have sex on the first date. I’m a virgin and only just begun to really put myself out there, so I’m having trouble imagining how to be comfortable being so vulnerable and intimate with someone I’ve only met 3 times. How can I trust them to respect my body and my boundaries, if I’ve only known them for so little?

I’ve heard advise saying that many men will assume that I’m not attracted to them if I’m not excited to sleep with them, but how can I be comfortable if I hardly know you? Some have said 3 dates is a long time, but surely it isn’t hard for someone to be inauthentic for 3 days if they don’t actually want something serious and just want sex, right?

Also, some have said that they want to have sex asap to determine sexual compatibility. How would that work for me if I’ve never even had sex?

Is it unrealistic to expect a committed relationship before having sex? In my ideal world, I’d know I really like someone before taking that step, but I can’t imagine seeing the potential for love in a few hours. Would it be better for me to get over this hang up over sex if I want to date seriously? Brutal honesty and advise would be greatly appreciated. I promise I can take it 😉