I think it's time to see your doctor. If you're loosing weight in a way that's not normal for you and without any effort, that means something's up. Hopefully it's something easily fixed, but it's possible it is serious and even potentially has nothing to do with your thyroid.
Make sure you tell your doctor about any abnormal bowel movements/ diarrhea, bloating, abdominal pains, nausea, excessive sweating, elevated heart rate, increased urination or thirst, fatigue, headaches, brain fog, etc.
I would suggest you talk to your doctor about testing your thyroid- are you on medication? Perhaps that pushed you to hyperthyroidism. Do you have Hashimoto's? Because that can cause periods of thyroid "storm" where your thyroid function is elevated, which can push you hyper. Also, ask about getting a blood glucose level done, to rule out diabetes. You are young, but you are overweight and unexplained weight loss is a symptom of diabetes. Also if any foods seem to make you feel ill, perhaps you need to rule out food intolerance or allergies which could explain the weight loss.
im eating and drinking the same as always. my apetite hasnt changed. ive been to the dr for my thyroid problems, and sometimes my levels are normal and sometimes not. but ive never lost weight without trying. its always been a really hard thing to do. i dont understand it.
Do you feel well have you any symptoms ,when you say you have symptoms of hypothyroid has it been checked by the doctor .It does sound a lot to lose so quickly are you eating drinking okay, have a good appetite ?