Here are a few corrections you could use. "I love seeing the cherry blossoms. But recently, I’ve started to feel differently. Now I realize how short life is and how uncertain the future can be. Who knows if I will see the cherry blossoms again next year? When I was younger, I never thought about things like that." "I’ve always loved watching the cherry blossoms bloom. But lately, they’ve made me reflect on how short life is and how uncertain the future can be. Who knows if I’ll still be here to see them again next year? When I was younger, I never gave these things much thought." "I’ve always enjoyed seeing the cherry blossoms. Lately, however, they have given me a different feeling. They remind me of how brief life is and how uncertain the future can be. Who knows if I will see them again next year? When I was younger, thoughts like this never crossed my mind."

I love to see the cherry blossoms. But lately I've had a different feeling. Now I realize how short my life is and how uncertain I am. Who knows if I'll see the cherry blossoms again a year from now? I never thought about it when I was young.

I love to see the cherry blossoms. But lately I've had a different feeling. Now I realize how short my life is and how uncertain I am. Who knows if I'll see the cherry blossoms again a year from now? I never thought about it when I was young. For the most part this is grammatically correct, but at times your tense choice sounds a bit unnatural. I have always loved to see the cherry blossom, but lately I’ve had a different feeling. I now realise how short my life is, and how uncertain it is. Who knows if I will see the cherry blossom a year from now. I never thought about this before. Also you may want to change lately I’ve had a different feeling To Lately my feelings have changed Both are correct but changing the subject makes the text a bit more interesting. All in all, this is a super fun text. Conveys some cool ideas and was fun to think about, thank you. If you have any questions let me know :)

I love to see the cherry blossoms. But lately I've had a different feeling. Now I realize how short my life is and how uncertain I am. Who knows if I'll see the cherry blossoms again a year from now? I never thought about it when I was young.