You don't, have never had, and will never have your own standards. You have standards you've borrowed from everyone else. Sorry in advance.
The fact is, I honestly believe you can discriminate sexually however you please. Race, gender, bad breath, wealth, what-the-fuck-ever. You get to have sex with whomever you want. No one owes you sex, you owe no one sex, ergo there's no such thing as discrimination. Become a nun, go into porn, your call. Your body, your choice. Your choice doesn't have to be a good one, it doesn't have to be an ethical one, it is just your choice. I also think no one has to the right to criticize who you fuck or don't because they don't have to do it. It is the singularly most intimate and personal choice. It's your choice, and it need not be politically correct.
But I think you want to talk about ethics. Because you say it IS wrong to discriminate based on number of partners, and I disagree. You can discriminate based on the brand of chewing gum they prefer, see above. You don't owe sex and you aren't owed sex, so discriminate as much or as little as you want. But how you SHOULD discriminate? That's a different question. And that's really the question you're asking.
I think the why and how matters so much more than the number.
Which makes the number...pretty fucking irrelevant to me. But the number is the tried and true standard of what you named as the prude or the misogynist (and if you're really claiming no genders here, I'd go with promiscuous since that's gender neutral, even though you're clearly labeling yourself). Those standards are built into the number, and the number is built on gender, and it comes from history and it is never a-historical or a-political. It lives in a time, a place, a rhetoric, a social norm, an expectation, and the breaking or acceptance of that expectation.
A couple of examples. It was not adultery to sleep with your slaves. That was just good business. It was not considered homosexual to have mutual masturbation on a ship in the 1900's. That was considered just helping out a friend. Brothels were, at times, promoted in America as a necessary public service so men wouldn't overtax their wives with the burdens of sex. Because, of course, sex produces children. Children produce child birth. Child birth produced death. Better to kill a whore than your wife, right?
Right now, there's a correct number of sexual partners to have. None is seen as shameful outside of specific circles. A lot (and everyone draws this line differently, depending on their cultural background and sexual morals and high school sex education and the reports of their peers and any number of other factors) is seen as shameful too. You're not making that number out of the ether. You're taking that number from everyone around you and making it your own. If it was socially shameful for everyone to have not fucked at least 100 separate people before marriage to prove that they have the sexual capacity to satisfy a man or woman for life, you'd take that number as shameful. We have looked at concubines as the most desired and cultured women in the world. We've looked at whores as the most disposable alternatives to not killing your wife. It's all perspective.
Your perspective is valid to you. It always will be. No one can make you want a thing you don't want. But, at the same time, it is always of its moment and culturally constructed and coming out of the fears and anxiety of the times.
Your feelings are always valid. Your numbers are not.