So this Krishna science can be understood through the process of sincere service, and so far any doubt which may sometimes arise in our mind there are the devotees, the Scriptures and the Spiritual Master. Did you discuss all your doubts with your contemporary Godbrothers and devotees? So there are many questions like this about you.
You say that within your heart you know that Krishna is the Original Personality of Godhead but when you think of Krishna or try to feel Him you think Krishna as foreign on account of Sanskrit language. Please, therefore, be careful that Maya is peeping at you and if you do not take care timely it may prove fatal. Please, therefore, chant regularly without the offenses and be steady in your situation without any tottering of the mind. Krishna is the Supreme Personality of Godhead without any question. He is accepted as such beginning from Arjuna through all the great Acaryas—Ramanujacarya, Madhvacarya, Sankaracarya, Lord Caitanya, Lord Brahma, the Vedic authorities Vyasadeva and Narada—like that, down to ourselves.
So this knowledge descends through bona fide disciplic succession. You have accepted this chain of authorities, now you are feeling doubts means certainly you are being attacked by Maya.