Normal ranges for TSH vary by lab, but the American Thyroid Association recommends 0.3-3.0, though most labs use a range of about 0.45-4.50 or 0.5-5.0 or something like that... if you have the lab reports, they should have the ranges on them.
Your results are all within normal ranges; the problem is that TSH, alone, doesn't tell the whole story. Have you had any Free T4 and Free T3 tests done? Those are the actual thyroid hormones and you need to have those tested in order to know what your actual thyroid thyroid function is...
TSH can vary, so yes, it's normal for it to be different each time you have it tested.
Are you having symptoms of either hyper or hypothyroidism? Please list your symptoms, along with results for Free T4 and Free T3 if you have them. Also please list reference ranges, which vary from lab to lab and have to come from your own reports.
Why did you have TSH tested just a couple weeks apart, in January and February of this year? That's quite unusual...
Multi-nodular goiter is quite common and often accompanies, both, Hashimoto's Thyroiditis and Graves Disease... Have you been tested for thyroid antibodies to determine if you have either of these conditions?
To test for Hashimoto's, you need Thyroid Peroxidase Antibodies (TPOab) and Thyroglobulin Antibodies (TgAb). The definitive test for Graves Disease is Thyroid Stimulating Immunoglobulin (TSI). You symptoms would determine whether you need all 3 of these or not.