My tsh level is 7.5 with normal t3 (liothyronine) and t4.my age is 28 and i am married.what can be possible reasons for it?

TSH 7.5: You have mildly low thyroid levels. I would check the TSH again with a tpo antibody level. About 50% of people will return to a normal TSH when check again. If your TSH remains slightly high and your tpo antibody is positive, this predicts you will develop more severe hypothyroidism in the future so i would start levothyroxine therapy. If it goes back to normal, repeat the TSH in 6 months.