thanks for your query.
Please consult a proper infertility
specialist for further treatment.
As all your tests are normal, which you have mentioned, then IUI ( intra uterine insemination ) seems the best way for you.
The major cause of infertility is unexplained infertility, in which no definite cause can be found.
In such cases, sometimes, there might be some local or cervical factor, which can be overcome by IUI.
As such, by wasting time without treatment, your age would increase and age related problems would arise.
You should definitely try to go for IUI, if you have already spent three years trying to conceive naturally.