Hello there!

That was a nice funny story. It just reminded me of my same experience with food when I was in military service. Thank you! ^-^

Just to share some ideas with you:

I understood from your opening that you wanted to tell a story that has happened in the past (using "was" in first sentence). Therefore, it is more proper to use the rest of the verbs accordingly.

Also it will make the writing more beautiful and eaiser to read if we use space, dot, and coma properly.

speak of cooking (how about naming the title as "The Rice Cooker" ? :d)

When I was at college, my (better use "our" to fit with your next sentence) dormitory is (was) small, and we dont (did not) have any kitchen, (so) we can (could) only go to the college canteen. (,) (but its food) the food in there is (was) disgusting.
(Therefore) so girls in my dormitory bought an automatic rice cooker, (.) it is too small to cook many (since food is uncountable, better use enough or alot of) food.
but we are (were) very greedy.
Once,we wanted (decided) to make the (no need) mutton soup,but the automatic rice cooker is low input power,it cooks slowly.
we cooked 3 hours!!! (You know what? It tool 3 hours to cook!)
we almost died ("out of" or "because") of starvation.

Now please take a look at this and let me know what you think:

"The Rice Cooker"

When I was at college, our dormitory was very small and we did not have any kitchen there. We could only go to the college canteen which its food was disgusting.
Therefore, girls in my dormitory bought an automatic rice cooker. It was too small to cook enough food for all of us because we all were very greedy.
Once, we decided to make some mutton soup but the automatic rice cooker was a low-power and very slow cooking one.

You won't believe it! It took 3 hours to cook!!!
We almost died out of starvation.

I hope this could help.I'd be happy to answer any question.

Regards

Hamzy

我们相互改吧。。。没人改我的。。。

speak of cooking

When I was at college,my dormitory is small,and we dont have any kitchen,so we can only go to the college canteen.but the food in there is disgusting. (时态是否都用过去式比较好?)
so（therefore如果避免重复） girls in my dormitory bought an automatic rice cooker,it is too small to cook many food.
but we are very greedy.
Once,we wanted to make the mutton soup,but the automatic rice cooker is low input power,it cooks slowly.
（youknowwhat）we cooked 3 hours!!!
we almost died (because）of starvation.

挺好吧。。。多用连词！时态都用过去比较安全。不知道是不是toeflspeaking的话题 时间控制到时类似于托福.自己感觉加了黑色后顺一点点，但是我英语差 勿喷。。。