Most Helpful Guy
The biggest problem is probably going to be the combination of your age plus the fact that you are very attractive (if it's you in your profile pic, anyway).
Because you are really pretty, you are going to draw the attention of a lot of alpha males. And a lot of alpha males are not 'good guys', because the personality traits that give them the confidence to pursue numerous attractive women also tend to be the same kind of personality traits that make a guy seem like a jerk or douche bag.
A nice, pretty girl that is starting to have confidence/esteem issues because she has been struggling with men is like blood in the water to a bunch of sharks. You are going to be like a beacon to players, which will just make your experiences worse, which make you more vulnerable to even more players who are able to say the things you want to hear.
Since you can't really do much about the way you look, you are always going to be attracting guys that are players. BUT, it will be much worse if you tend to spend time in areas that are frequented by players. So if you are meeting guys in bars, or at dance clubs, you are never going to be able to get out of that spiral. If you want to find nice guys, good guys, you have to put yourself in the locations where those guys are found.
Guys that are older is one solution, as the douche bag nature will occasionally start to dissipate after their prefrontal cortex is finally finished developing in their late 20s. But beyond that, it will depend on things like hobbies. Think about hobbies you like, and then think about the types of hobbies that guys would have that match some of your criteria. And then make sure you are at the places where that happens, or in the clubs that deal with it. Certain groups at university can be good bets. Or running groups. Or tabletop gaming groups. Or dance class. Whatever, doesn't matter, as long as you have a bit of interest and there will be guys there that have those interests that won't necessarily be alpha males.
And to be honest, there is no way that someone that looks like you is going to be lonely forever. It just may take multiple years for the types of guys that you want to find you will develop the nerve to pursue you. Until then, it will be the aggressive types.
Most Helpful Girl
Maybe try being single for awhile. It's nice to have a guy and all that, but if you keep having such bad luck maybe it's time to just focus on yourself... Once you try to make yourself happy and not worry about "finding love," a lot of good things will happen and you can start attracting better guys. Good luck. It's not easy out there.