Is it possible for 25 mcg of levothyroxine to normalize my hypo thyroid (hashimoto) right away or is it possible that it normalized itself?

Yes: It will take a few weeks to see if it has. It is unlikely to normalize on its own.

Depends on the TSH: Your dose of levothyroxine is tiny, just about the lowest. When you have low thyroid function your TSH is high, above 4. Taking the levo lowers it to normal by adding more thyroid hormone to your blood. So if your TSH is now less than 4, then you are O.K. On the other hand, if you require only 25 mcg, you probably have a thyroid that is just abouit normal and do not need any thyroid medication.

Low dose: 25 mcg is a very low dose, and most people who are completely hypo need more. Hashimotos can take many different courses, from progressive permanent hypo, to a transient thyroiditis with hyperthyroidism, to things in between. From your question it is hard to know where you are. You may want to consult an endocrinologist.

Hypothyroid: Hashimoto's is an autoimmune problem that means the body is fighting itself for unknown reasons . Levothyroxine will help achieve normal function and not feel tired or gain weight. The function of a thyroid once compromised does not usually return back to normal.