I'm sorry about the family pressure that you are facing, but I'm proud of you for following your path. If you don't want to be a software engineer, then work hard to achieve your goal. Believe in yourself! Retake if you want.
As with any book, studying using Loophole is better than not studying at all. But if you would reverse-engineer 15 LR questions on your own instead, it would be much better and faster.