The day that my parents bought me my first Tarzan..Penn Supp

Can someone please help me fix this sentence. It seems like something's wrong with it. I want to make it as much as a hook as possible.

The day that my parents bought me my first Tarzan 100 piece Jigsaw Puzzle back when I was in first grade, was probably the biggest regret of their lives. From then on, there was no going back.

Please Help! It's really Easy!

My parents' greatest regret was probably buying me my first Tarzan 100 piece Jigsaw Puzzle in first grade. From then on, there was no going back.

Though this version is better, it stills seems mighty awkward and not too much of a hook. Maybe try to rearrange the words a bit more?

Great job, Julie! I'll try to improve it even more...
My parents' greatest regret was is probably buying me my first Tarzan 100 piece Jigsaw Puzzle in first grade when I was six years old. From then on, there was no going back.

I took out some words, because it is always good to take out words if you can.

:-) And I got rid of 'first grade' because it is awkward to use first 2 times.