I think I'll post a simple conversation.

SI am so hungry.

I wonder if I should get a Japanese set meals?

I'm wondering if I should choose a Japanese set meals?

Molly：I'll have the tomato and garlic pasta set, and dessert after the meal.

I'll have the Japanese set meal and a coke after the meal.

I usually usehad the heater on, but it was still really cold,

暖房をつけている simply states that you had the heater on at that moment and does not really state that it is a habit (i.e. usually).

so I turned up the heat.

With that, I think I'll post a simple conversation.

Added the それでは nuance for the transition.

IThis time, it’s a situation where you decide what to order while looking at the menu.

Added 今回は

SI am so hungry.!

I think it is more common for this line to use the full sentence even for casual conversation.

I'm really hungry becauseTotally! I haven't eaten anything since this morning, so I am starving.

A lot of it is about the tone when it comes to casual conversation. Your line is correct too, but it just feels a bit monotone. There are many ways to express the same thing. It's more about expressing the emotion than being grammatically correct.

(While we checklooking at the menu…)

Molly：WHmm.... what should I get?

Just adding the "thinking" part of かな

Ellie：: Ah..., I can't decide what to get.!

I wonder ifMaybe I should get athe Japanese set meals?

Molly：Think I'll have the tomato and garlic pasta set, and then a dessert after the meal.

Ellie : What comes with the pasta set menu?

The pasta seIt comes with the pasta, a salad, a soup, and a drink.

I’'m wondering if I should get a cup of coffeethinking about getting a coffee for the drink.

or I wonder if I should get a cup of coffee.

Then I'll have the Japanese set meal and a coke after the meal.

The "Then" gives a sense of "I have finally made up my mind after hearing about what you are having" nuance.

I usually use the heater, but it was still really cold,

If we're talking about today now, it might be good to specify, "...but it was still really cold today." (Or, "...but it's still been really cold today.")

so I turned up the heat.

I think I'll post a simple conversation.

It’s a situation where youpeople are decideing what to order while looking at the menu.

Ellie ：

SI'm so hungry.!

I'm really hungry becauseYeah, I'm starving. I haven't eaten anything since this morning.

I think I agree with another user's post on this matter. This sounds a lot more natural.

(While we checking the menu…)

Is one of the people in this conversation you? The use of "we" would imply that you are in this group.

I wonder if I should get a Japanese set meals?

I'm wondering if I should choose a Japanese set meals?

The former with "I wonder if..." sounds more natural to me.

Molly：: I'll have the tomato and garlic pasta set, and dessert after the meal.

A "desert" is a dry, arid environment usually covered in sand. But "dessert" is a type of sweet food for after a meal. Actually, I'm a bit embarrassed to admit that I just had to look up which was which to make sure I hadn't gotten them mixed up.

Ellie : What comes with the pasta set menu?

The pasta set comes with a salad, soup, and a drink.

Alternatively: "It comes with a salad, soup, and drink."

or I wonder if I should get a cup of coffee.

Yet again, the sentence with "I wonder if..." sounds better to me. You might hear both, though.

Alternatively, we might say, "Maybe I should get a coffee?"

Ellie : Sounds good!!!

I'll have the Japanese set meal and a coke for after the meal.

I think "coke" is *technically* supposed to be capitalized since it's (an abbreviation of) a brand, "Coca-Cola", or just "Coke". However, I'm not sure if this actually matters much.

SI'm so hungry.

I'm really hungry becauseYeah, I'm starving. I haven't eaten anything at all since this morning.

The original sentence is correct. This correction is another way to write it based on the original text and to make it sound more casual, since this is what the situation seems to be.

(While we checklooking at the menu…)

Original sentence is correct, this is another way to write it. Both are about the same in terms of sounding natural.

I wonder if I should get a Japanese set meals?

I think this one sounds more natural than the other version of the sentence. I also agree with ghelgheli's suggestion that you can use "combo" as well.
Another option that is a little more casual sounding: "I wonder if I should go with a Japanese set meal."

or I wonder if I should get a cup of coffee.

I think this version of the sentence sounds more natural.

so I turned up the heat.

I think I'll post a simple conversation.

I wonder if I should get a Japanese set meals?

You could also say "combo", though that might be less specific than "set meal" (but it sounds more natural).

I'm wondering if I should choose a Japanese set meals?

Ellie : What comes with the pasta set menu?

I'll have the Japanese set meal and a coke after the meal.