You can have Hashimoto's and a normal TSH. TSH can be a good indicator that there is a problem if it is out of range, but many people have thyroid problems with a normal TSH. Do you have hypothyroidism symptoms? Did they test for free T3 and free T4 also? If you have these test results and want to share them here to that would help to identify whether you have a thyroid hormone problem.
Have they tested you for anti-thyroid antibodies? Hashimoto's is usually diagnosed by testing for anti-thyroid peroxidase and anti-thyroglobulin antibodies.
A heterogeneous thyroid echotexture is often a sign of Hashimoto's, but thyroiditis (inflammation of the thyroid) can be caused by several different things, including bacterial or viral infection, certain medications, and being post-partum. Hashimoto's is by far the most common cause of thyroiditis, but it isn't the only cause.
Hopefully this helps. If you suspect you have Hashimoto's, I would push for your doctor to test for anti-thyroid antibodies.