Thyroid Cancer patient here...?

In January, I had my whole thyroid and 12 lymph nodes removed. Four days later I was told it was cancer. Three weeks ago I had my RAI treatment and I've been depressed ever since. I go today to hopefully get my hormones upped. I take 250 mcg. But the past few weeks all I've done is sit around and cry. I have two small children, a 2 year old and a special needs 6 year old. I'm a single mom also. I don't know what else to do. I feel like the worlds biggest burden an worst mom cause I feel so awful still. Could this be from my medicine not being high enough or maybe something more?? I feel like I'm losing my mind...