Oh my gosh. I know you are older than me, but you're sooo cute! I love writing multiple paragraphs (no offense). I tend to write way too much on my writing projects, so I'm sorry I can't help you very much on that. However, I can say that 20 words in a sentence is to me, just plain stupid.
Don't worry, writing can be easy if you have a good, open ended topic to write about. Try not to add small details, but make your writing detailed. In other words, instead of putting what you had for breakfast in a story, try to imagine an important event, or your feelings on a subject/event. Make sure that you make every single point you need to, and if you feel your writing is too short, add support sentences. If you do that, you'll have five paragraphs in no time!
(Oh jeez, I already wrote a lot. Although, i did that by-going back on what I previously said- stating all of the necessary points I wanted to discuss, and using support sentences. Tust me, it works.)