This Is A First For Me- No Pattern!!!

My toddler has recently gotten a larger bed and now her old bed sheets don't fit. Well the top one still does but there is no hope for the fitted sheet... or is there? I have decided to take on a seriously challenging refashion for me. I want to turn this sheet into a dress! I have never made anything with or without a pattern though. Because this is challenging and a lot harder than I expected I have not finished this one yet. Im going to post it anyway though in hopes I can get some advice and suggestions from you lovelies. Once I finish it I will come back and either update this post or link to the next phase of this refashion. So it will be like part 1 and part 2!

Heres the sheet. Its a "Frozen" bed set.

First I cut off the elastic band:

Then I cut into the corners so it would lay flat:

Then I got out on of my toddlers dresses to determine the size of the neck and arms. Note: I am NOT going to make a copy of this dress- just using it for sizing. I plan to make more of a mumu style dress with no sleeves.

I got out my fabric pencil and started tracing.

Next I folded it in half with the intent of cutting so that both sides are the same. But I didn't cut yet! I stopped there because I thought I better seek advice before moving on. Just in case.

So- any helpful advice for someone who isn't a super great sewer and has never used a pattern?

Update coming soon!!!