pThe Persimmon Tree

There is a persimmon tree that was planted by a previous owner at my sister's house.

The tree hadalways bears a lot of fruits also as it had this year, but my sister don’idn't eat them a lot of them.

"Fruit" can be both singular and plural in the US.

So my parents gotpicked two buckets of persimmons and brought them into to our house.

美味しそう！羨ましい〜！

However, nNeither my sister nor my parents don't, however, eat a lot of persimmons.

残念。

neither ... nor → these are negative so we use an affirmative verb with them to state a negative

If so,So who eats all of thoese persimmons?

Since this is the case, who eats those persimmons?

For the past few days, I've been eating one or two at a day, but I've gained a little weight, which I had started to lose.

あっ、残念！I'd eat them anyway, lol. They're just fruit and fruit is good for us!

Fruit contains more sugar than I think, so I must to be careful.

There is a persimmon tree in my sister's house that was planted by the previous owner at my sister's house.

The tree hadbore a lot of fruits also this year, but my sister don’idn't eat them a lotmost of them.

Depending on what idea you want to convey, you could also use:
"but my sister didn't really eat them"
"but my sister didn't eat much of them"

So my parents got two buckets of persimmons and brought them to our house.

However, neither my sister nor my parents don't eat a lot ofeat persimmons.

If so, who eats those persimmonsthat's the case, then who eats them?

Normally I would be very happymore than happy to eat them, but now I'm on a diet, so I'm a little stuckrestraining myself.

We don't really use the word "stuck" in that sense so I changed it to "I'm restraining myself" because I think it sounds more natural. :D

For the past few days, I've been eating one or two at a day, but I've gained a little weight, which I had started to lose.

Fruit contains more sugar than I think, so I must to be careful.

You can either say "I must be careful" or "I have to be careful"