Yup, training is the best way to start getting your extended combos down. Also, lag may cause your combos to drop online, especially if you have to input a JF.
Rage and frustration are parts of the game! And while it's perfectly OK to get salty over something you didn't do well on, it's also important to reflect on your mistakes and try to improve those aspects of your game. Did your poor positioning cause you to get rung out? Did a lack of practice/playtime cause you to drop some combos? Were your attacks so predictable that your opponent knew how and when to counter? etc.
Anyways, welcome to 8WR! We've got a really nice community here, so if you have any questions, just ask!