I Have Low Thyroid And Treating With Synthroid 88mg. For

I have low thyroid and treating with synthroid 88mg. For years but I'm having symptoms like it's not working is a constant headache as well as cold fatigue moody etc... Be something I need to change mg.? Got blood work done from primary dr. They say it's ok. But I never get the actual numbers from them. I think it needs changed. Headache is still there. No back problems