160m:
Sounds like a mild case and not very typical as you can ejaculate with oral and sometimes vaginally. I think that as long as you don't masturbate for a day or two before being with your g.f. you should be OK. And, from the tone of your post, it doesn't sound like it's anything more than a slight inconvience. Certainly if it gets to the point where you get the most common kind of RE- where you can't ejaculate at all, by any means other than self masturbation, then it's time to get some help.
Sometimes younger men get these mild cases and it goes away after a few years. The true test is sex in a long term relationship where you have grown used to the partner and start getting bored. For most men, who don't have RE and don't masturbate every day, sheer horniness will carry them through successfully,
even though they may have lost interest sexually in the partner. But men who suffer from even mild cases of RE may find their problem getting increasingly worse in this situation. Many then turn away from the partner and practice self masturbation exclusivley. This is when the condition becomes extremely difficult to treat.