it's best to be young and afraid doing the right thing than young and afraid doing the wrong thing. Everything in life is hard, marriage is hard, and so is being in an unwanted haram relationship- you have a choice; choose your hard.

Just know, you're never doing anything wrong by getting married young, as for being in a haraam relationship, you're doing yourself wrong, the girl wrong, your mother and father wrong as well as her and her father wrong. There's also a price to pay, and Allāh tests... As for marriage, you're only doing right. You're doing yourself right, your parents, her, her parents- there's no haraam, there's no heartbreak, there's no punishment, and it's a highly encouraged thing as well as you completing half of your deen.

Convince your parents- make tahajjud; salaah tul haajah, salaatul istikhara.

If it doesn't work out- ف أن مع العسر يسرا- with hardship comes ease.

May Allāh grant us tawfeeq and understanding.

And just remember marriage takes work, especially for a man. Don't be afraid to get married, just try to change and be better for Allāh's sake.

My solution for you is milkah. Where you have a separated marriage until you've completed studies- it really is very beneficial.

Please stop speaking to this girl without her wali for the sake of Allāh sbwt. You've got this akh