All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
First of all, we welcome you in our website and we ask Allaah to guide you to do what is good.
As regards your question, since you believe in Islam and you believe that it is the true religion, then we think good of you if you concretise this belief by uttering the two testimonies of faith, which is to say: "Ash-Hadu Alaa Ilaaha Illallaah Wa Ash-Hadu Anna Muhammadun Rasoolullaah" (I testify that none has the right to be worshipped but Allaah and I testify that Muhammad is His Messenger). So, dear honourable questioner, take the initiative to utter this testimony of faith while truly believing that none has the right to be worshipped but Allaah and that Muhammad is His Messenger. Then you may pray and fast and get the great reward from Allaah. What prevents you from embracing Islam since you believe in it? We remind you with the saying of Allaah (which means): {O mankind, the Messenger has come to you with the truth from your Lord, so believe; it is better for you.}[Quran 4:170]. Allaah further Says (which means): {If only the People of the Scripture had believed, it would have been better for them. Among them are believers, but most of them are defiantly disobedient.}[Quran 3:110].
For more benefit, please refer to Fataawa (plural of Fatwa) 86969, 88906, 88195 and 81979.
May Allaah open your heart to embrace Islam and we will be very happy to hear the good news.
Allaah Knows best.