Most Helpful Girl
I know you said you're not fishing for compliments, but you would get far better answers if you posted a photo. Also, you may be getting compliments from older women because they are more confident . They wouldn't be intimidated by you because you are younger.
Anyways, your height is good for modelling. I think agencies look for guys with a strong bone structure, and interesting features, like something that sets you apart from the average guy on the street. That may be large lips, wide set eyes, big bushey eyebrows or whatever. You don't always need to be super muscular for runway anyway, so that's not a problem. You would probably get more work if you did have a toned body though. The best thing to do is send some photos off to different agencies and see what they think, because being "hot" isn't always what they're after. Sometimes having an unusual/quirky look is very appealing to them also. You should definitely go for it, and try your luck. A friend of mine landed a Burberry campaign not too long ago, and he's travelling the world working. Good luck!