Should I go get more medication?

I was feeling extra tired and weak and I thought it was from working(military dental tech) and caring for my eight week old and my four year old alone(husband was deployed). But after a blood test I was diagnosed with Hypothyroidism. I was prescribed a small dosage of Synthroid and told to come back in a month. I'm not a very good "pill taker" so I took the pills here and there, I didnt go back to the doctor and didnt think much of it because I felt pretty normal most of the time. But lately I have been feeling more and more tired and weak to the point where my legs or arms tremble. Some days its hard to wake up, its like I'm so tired but I make myself get up and i just tell myself that I'm being lazy. But am I? Do I really need to go back and get another blood test or more medication? I think my thyroid levels may have gotten lower because I didnt take my medication properly and eventually quit taking it. Should I be concerned? Is hypothyroidism more serious than I thought?
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Synthroid MUST be taken regularly!!!!!!!
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