Hi
I am constantly tired and have also had lots of tests and there is nothing wrong with me! I have done depression tests and am not particularly depressed either!!! Being anxious takes a hell of a lot of energy, add life to that.... work, kids, partners, etc and there is bound to be little left if anything.
Do not get caught up in the depression thing, it is only something else to worry about. Are you eating healthy food, getting enough exercise and fresh air, is your work stressful, do you have fun with your kids? I could go on but when I started to look at each individual item in my life, I found that not all was as I thought. For example.... being with my kids was a chore, I was eating loads of chocolate, not doing much in my spare time, etc.
All these things will make you tired so look at the whole picture if you can.
Not sure if this helps or not......