I am the opposite...been on synthroid since radiation ablation in the mid-90's. I have been on the same dose (112 mcg) ever since until the last 8 months. Synthroid is not fast acting but is much easier to maintain consistent thyroid levels . You tend not to have huge swings if you take it consistently each day. I would be very reluctant to try anything else at this point but just my POV.
What are your current levels? If you have recent labs (with reference ranges) to post, it would be helpful.
It's not unusual for levels to fluctuate over time or to need medication changes as the thyroid varies output as it "dies off". You do have to be sure your doctor is basing your dosages on actual thyroid hormone levels and not just TSH. There are a variety of things that affect TSH and make it fluctuate so trying to adjust medication on that basis is like trying to shoot a moving target.
Personally, I've been on quite a few different med(s)/dosages over the past 15 yrs. Meds have included Synthroid, generic Levothyroxine, Tirosint, Levoxyl (all T4 meds), Cytomel, Liothyroinine (T3 meds), NatureThroid and I'm currently on Armour Thyroid. Dosages have ranged from 50 mcg to 112 mcg of T4, 5-15 mcg of T3 and my current dose is 60 mg.
There have been times during which I've felt "better", but I've never really felt "good" on any of the dosages. My current dose of 60 mg is not enough and I've been supplementing it with extra T4.
I do have other conditions such as Pernicious Anemia, adrenal adenomas, etc that contribute to symptoms, so I can't blame it all on thyroid. However, my last test results showed, Free T4 below range and Free T3 very low in the range. At that time, my dose of Armour was increased from 3/4 grain (45 mg) to the 1 grain (60 mg) I'm currently taking. I'm due for blood work again next month, but judging from the way I feel, my levels will be normal, even though I still have symptoms.
I was on 60 mg of Armour for 2 months, I have 112 lbs and I could tell you that 60 mg of Armour is not enough. Not even 90 mg of Armour was not enough. It gave me hyper symptoms because my free T3 was in the higher range but my free T 4 was in the lower range0.9 and the lower range is 0.8. I stayed on the 90 mg armour for 3 months and I felt bad. Then i added 25 mg levothyroxine generic i addition to 60 mg armour. Still after a month my Free t4 was 1.0 at this point i felt so hypothyroid. I could not bear the fatigue and I ask my doctor to give me 88mg levothyroxine generic in addition to 60 mg armour. 10 days into it and I feel much better. I know that this dose might be too much but I just could not wait to be so fatigue...
I was on Levothyroxine 88 mg before Armour for 9 months I was ok but felt something is missing..thats why I started on Armour....however armour you need to take at least 2 .5 grainsto take the level of Free T4 to a good level. But at this point free T3 could be so high that might cause other problems. So I dont know if is healthy to be on that much Armour. Thats the way I think. When i made the transition from levothyroxine to armour i felt the best for a month until my free T4 reduced to almost nothing