Salam o Alikom
I think brother that your thinking is one of the gate of whisper (waswaas) of shaytan. to fail in something you like to do dose not mean because your sin. Maybe allah (swt) push evil from what you are doing.
كُتِبَ عَلَيۡڪُمُ ٱلۡقِتَالُ وَهُوَ كُرۡهٌ۬ لَّكُمۡ*!ۖ وَعَسَىٰٓ أَن تَكۡرَهُواْ شَيۡـًٔ۬ا وَهُوَ خَيۡرٌ۬ لَّڪُمۡ*!ۖ
وَعَسَىٰٓ أَن تُحِبُّواْ شَيۡـًٔ۬ا وَهُوَ شَرٌّ۬ لَّكُمۡ*!ۗ وَٱللَّهُ يَعۡلَمُ وَأَنتُمۡ لَا تَعۡلَمُونَ (٢١٦)
''Fighting is prescribed for you and ye dislike it.
But it is possible that ye dislike a thing which is good for you, and that ye love a thing which is bad for you. But Allah knoweth and ye know not''. (216) Al-Bakara
However your thinking should encourage you to avoid sins and make more good deeds.
beware from those thinking it open gates for shaytan to put your mind down.
I would like to share with you some link talking about whispers(waswaas).
http://www.islam-qa.com/index.php?ref=72307&ln=eng&txt=الوساوس
http://www.islam-qa.com/index.php?ref=3759&ln=eng&txt=الوساوس
http://www.islam-qa.com/index.php?ref=12315&ln=eng&txt=الوساوس
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you can check arabic version, they are more completed. i guess you sepack arabic . you can read more just search using as a key wordالوسواس
salam o alikom. and allah protect you from evil.