我從小，我幾乎什麼都會吃，並不是很挑食。

Since the adverb of time is really short, it is better to put it inside the phrase after the subject. As you claim that 幾乎什麼都會吃,there is no point in repeating the same idea immediately. 不是很挑食 means that you are picky but not that picky.

我唯一一個不太愛吃的食物是魚除了魚之外。

Since you have provided the context that you eat almost everything, it is clear that you are going to mention what you don't eat.

雖然我喜歡吃魚肉，但我害怕被骨頭噎住，所以吃魚時總是吃得非常慢，尤其是在吃那些特別是多骨的魚時。

吃 appears to frequently. In the first phrase, there is no need to explicitly add 吃, as you can't do much with fish meat. If you use 尤其, you should have an extra phrase elaborating on what happens when you eat fish bony fish. Since you don't, all you need in that phrase is "especially bony fish". You can omit all other words.

其實我發現，不挑食也有它的難處，因為我很難區別自己真正喜歡吃什麼。

You should not pause after 發現. 它的 is redundant.

每次吃飯要點菜時，我都會猶豫不定，因為每道菜聽起來我都有可能我都喜歡。

It is clear that you 吃飯 when you 點菜. Since you are reading the menu, the dishes can't be 聽起來 but 看起來. However, 看起來 and 有可能 together express so much doubt that you should not have problems deciding on what to order. It's clean to cut all of them out to focus on what makes your indecisive.

我唯一一個不太愛吃的食物是魚。

我唯一一個不太愛吃的食物是魚。

雖然我喜歡吃魚肉，但我害怕被骨頭噎住，所以吃魚時總是吃得非常慢，尤其是在吃那些特別多骨/骨頭特別多的魚時。

其實我發現，不挑食也有它的難處/壞處，因為我很難區別判斷/我不知道自己真正喜歡吃什麼。

每次吃飯要點菜時，我都會猶豫不定，因為每道菜聽起來我都有可能喜歡都很不錯/很好吃。