All of the hormones in your body must work together in order for you to feel well. We do have some members who have low testosterone, along with hypo/Hashi's. You should get your levels tested.
Hashimoto's is an autoimmune disease, which I'm sure you already know. Thyroid function sometimes declines quickly, with Hashi's and sometimes, it goes pretty fast. It's impossible to say.
What are your current lab results? You should be getting tested periodically, for Free T3, Free T4, as well as the TSH. Be sure to post reference ranges, along with results, since ranges vary lab to lab and must come from your own report.
TSH is a pituitary hormone and should only be used as an "indicator"; it should not be used, alone, to determine thyroid function or medication dosages.
Brain fog is a common hypo symptom. It sounds as though you may need an increase in your medication dosage.
Forgot to mention that simply being hypo can also cause low libido, even with normal testosterone levels.
Thanks for the reply.I don't have my current levels,but hope to see a doctor this month and i'll post the results.
Will look for them, here on this thread.