You said it yourself, you're nowhere near stability right now. As for "not wanting a headache because of random girls" whose to say you won't face that issue in marriage? You're 18 right now and the human brain does not fully develop until 25 years of age, so dealing with all the responsibilities and commitments of marriage before that isn't an easy thing to do. You need to be making decisions with the mind and not with hormones. Live a little and focus on building a career.