Both Ends of the Spectrum

Help. I don't know how to parent anymore.  I don't know if it's the span of my kids ages, 3 to 13, or what, but I'm losing my confidence in my ability to mother my kids.  Where can I buy a manual on how to parent a difficult three year old and teenager at the same time!?  

Parenting both of those ages at once is kicking me in the rear.  I wonder if this is what it feels like to have multiple personalities, one for the little kids and one for the older ones.  I feel like a fish out of water.  I truly feel like I can't breath sometimes.  Anxiety anyone?  I guess this is what you'd call a mid life parenting crisis. 

The youngest kids need to be read to, have help with their homework, and put to bed early.  The older kids think they have to do things with friends every weekend and stay out late.  Nothing can prepare you for this, nothing.  It is exhausting to say the least.  I know I'm not the first, nor the last that has and will go through this, but heaven help me.