I haven't had many partners in the past.
Nor have I. I think it's useful to realise that society is pretty hung up on this. Take any teen film and the pattern you almost always see is that the more enviable a guy is and the higher his social status he has, the more and prettier women he is dating or sleeping with. With relentless exposure to the implied idea that you need to date and sleep with lots of attractive women portrayed in the media a lot (it's not just films), I think we can see why it's seems to be a social norm that you're defective or something if you're male and not getting any/much.
I have a problem with self-acceptance myself due to this and I'm trying to get over it and though it is hard, I think I'm progressing. To give an example of how I think, if you had slept with a different model every month in 2014, you'd still be the same person today, with the same problems. You'd still have a PMO problem and you wouldn't have been promoted at work. It's just one area of life.
However, I do think that a man's dating life does indicate to some extent how well his life is going. I think if your not dating much at all, then you have some kind of problem that needs solving. Everyone has problems, so that doesn't make you a loser, but it seems to me that the label "loser" would be the conventional one for a guy with dating problems. Why is the guy who gets a leg blown off in the war disabled, but understandable with his problems but a guy who can't get dates a loser? Doesn't really make sense, but I think part of the issue is that you can see a missing limb. So try to respect yourself.
Also, I recommend using tick marks to see your "real progress", because resetting can otherwise become very disheartening.
TLDR
Don't label yourself a loser for not getting dates, your only bad at that one thing. Also, enable tick marks on your counter to help you feel more ok about resets and progress.