I just wanted to mention that you are probably THE BEST person (along with your husband) to care for your child. Please keep in mind that although home nursing agencies probably send many of their nurses to homes with patients with trach, vents, etc...many of those nurses aren't going to be as well trained as you when it comes to trachs (I've had some who had never worked with a trach or vent - thank god we knew what we were doing!
I always assumed full responsibilty for gaithy (our now 2.5 y/o) even when a nurse was here, because I never wanted to let them have 100% trust - they didn't know her like I did. As all others have mentioned, it gets easier and easier. We too had some scary moments the first week home - had to do two emergency trach changes thinking Gaithy way plugged. Come to find out it was a granuloma blocking the end of the trach, a granuloma that one of our home nurses had caused by not knowing the proper way to suction. After that I became much more vigilant. Still, nursing is nice to have for awhile, and I wish you luck in filling the shifts - you will need your breaks and alone time.