Hi Jess...
I think I can speak for everyone when I assure you that we're not going to judge you, or think you are an immature teenager. I know for one that there are not clear cut reasons for many of the things I do and if I have to try and explain why I self harm, go through phases of not eating or find it terrifying to go outside (to name a few) then I can't... its a part of this illness, so please feel that you can vent and get things off your chest and we are not here to judge you :)
As everyone else though - I would really encourage you to take your medication. As Zaf has suggested, is it possible to go back to your doctor? I don't really know too much about insulin, but it does occur that perhaps you need to increase your dosage back up??
Withholding medication that your body needs from yourself is a form of self harm, as I'm sure you are aware. I'm sure your doctor won't judge you for it, so please... I know its hard, because it feels like something else we are losing control of when we seek professional help for something such as this, but your body needs this insulin.
Take care Jess, we're all here to help if we can &*(