You have expressed a lot of the normal weightloss journey feelings, so welcome to the club.
You should check out the body image issues after weightloss forum section for info on loose skin and post-weightloss body advice.
Most specifically, the FAQ on loose skin: Weight Loss And Skin FAQs
However, I'll quickly summarize what you'll find in those forums.
-Loose skin may happen
-Being overweight for most of your life may mean your skin may mean more loose sking
-You may have NO loose skin
-Skin takes 1 year to fully adjust, so you have time
-You are YOUNG, which means more elastic skin and a great chance that your skin will tighten with you
What you can do:
Nothing really, loose skin is dependent on age/genetics/health history etc.
HOWEVER, building muscle tone can help fill the skin making it taut
Also, losing weight gradually gives your skin time to adjust
Bottom line, its not something you can really predict, you just have to make the leap of faith and see where it leads you. Please check out the aforementioned threads if you want more info about the factors that tend to affect loose skin appearance as well as recommendations by maintainers who are dealing with their post-weightloss body. There is also lots of information about tummy tucks are other surgery options if you feel that might be your path. Best of luck to you! And try not to stress too much about what might happen!