Please post the actual results of your thyroid bloodwork and include the ranges from your own lab report since these vary from lab to lab (both sets of labs would be good, if you have them). It can take up to six weeks for new meds or any meds changes to COMPLETELY take effect. 25 mcg is a very low dose, so it's quite possible that you need a meds increase before you will feel better. If your labs have hardly changed, it's a very good indication that you need a higher dose. Have you had thyroid antibody testing...TPOab (thyroid peroxidase antibody, sometimes calle "microsomal" on lab reports) and TGab (thyroglobulin antibody)?
My experience with the nodule, I had cancer though. I took less than 2 weeks for my med to work. Maybe they you increase dosage?