Because if she wants sex after two days , then it would tell me that she had probably already had sex with x number of men before
Not necessarily. In some relationships sex comes quickly and in some it doesnt. Sometimes with two people, they realise immediately what they want and so they do have sex soon after they meet and it's the right thing for them to do, for other people they have to wait because that's what right for them. And if someone wants sex after two days, it does not necessarily mean that they sleep around or anything like that. People are different and relationships are different.