I'm an 17 years old. My family has always been very secular. For a small period of time my older sister went to a Catholic school, and I was sent to Sunday school. When I was little I was very much afraid of death and the concept of eternal nothingness. This fear led me running to my grandmother's Bible for comfort. Anyway, at some point, this fear pushed me (mind you I was around 8) to promise God that I would pray a certain set of prayers every day before I went to sleep. I also promised that if I didn't, I would go to hell as a consequence. At the time I thought doing this would show my honor and commitment to God and somehow secure my family a spot in Heaven. Well, I pretty much hate myself for doing that. I do pray every day, for multiple times a day, but I do not remember exactly what I promised I would pray. The parts that I do remember are long, and I'm not going to lie, I've gone to bed without saying the whole thing. That part I know I can fix. I am genuinely sorry for not living up to my promise and embarrassed I made it in the first place. I have asked for forgiveness before but am scared. I've read your response to a question about breaking a promise to God, but what about this one? Do you think it's forgivable? What can I do?
Where did you find God saying a broken promise was unforgiveable? Solomon said, "Do not be rash with your mouth, And let not your heart utter anything hastily before God. For God is in heaven, and you on earth; Therefore let your words be few. ... When you make a vow to God, do not delay to pay it; For He has no pleasure in fools. Pay what you have vowed - Better not to vow than to vow and not pay" (Ecclesiastes 5:2, 4-5). Nothing in this verse says that a foolish vow cannot be repented of and, therefore, forgiven. "The Lord is not slack concerning His promise, as some count slackness, but is longsuffering toward us, not willing that any should perish but that all should come to repentance" (II Peter 3:9).
Nowhere does God say that any sin is unforgiveable. There are sins which people refuse to give up, but there the problem lies with man and not God. Take Esau as an example: "Looking carefully lest anyone fall short of the grace of God; lest any root of bitterness springing up cause trouble, and by this many become defiled; lest there be any fornicator or profane person like Esau, who for one morsel of food sold his birthright. For you know that afterward, when he wanted to inherit the blessing, he was rejected, for he found no place for repentance, though he sought it diligently with tears" (Hebrews 12:15-17).
Now, many of your problems lie in the fact that you made up terms for how you were going to worship God. You put yourself in the driver seat and imagined that God would be happy with whatever you decided to offer Him.
Rote prayers don't earn you salvation. "And when you pray, do not use vain repetitions as the heathen do. For they think that they will be heard for their many words" (Matthew 6:7). Prayer is your time to talk with your Creator, not to utter a string of now meaningless words. What you promised to God as a child was not anything God asked for or wants from you.
If you want to please God, you need to obey Him and not make up your own rules."He who has My commandments and keeps them, it is he who loves Me. And he who loves Me will be loved by My Father, and I will love him and manifest Myself to him" (John 14:21). Therefore, you need to learn what God wants and then conform your life to His teachings.