TAXI RTE ERROR AT PDX ARPT. NON ADHERENCE TO ATC INSTRUCTION CLRNC.

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BEING NEW TO THE ARPT I HAD REQUESTED TAXI INSTRUCTIONS FROM THE FBO TO THE ERT RAMP AT PDX. TAXIING TO AND CLRED TO CROSS RWY 10R; I WAS INSTRUCTED TO CONTINUE ON 'TXWY E' UPON APCHING RWY 10R. I ASKED THE GND CTLR WHICH WAY DID TXWY E GO; TO THE L OR R. HE SAID HE LOST SIGHT OF ME; SO I TURNED ON MY LNDG LIGHTS AND TOLD HIM I WAS HOLDING SHORT OF RWY 10R ON TXWY E AND FACING A 747 PARKED ON THE RAMP. HE TOLD ME TO CONTINUE AND AS I CROSSED RWY 10R; I LOST SIGHT OF TXWY E AND BEING IN FEAR OF BEING ON A RWY I TOOK WHAT I THOUGHT WAS THE QUICKEST WAY TO EXIT THE RWY; IT WAS TXWY F AND NOT TXWY E. AS THIS HAPPENED; THE CTLR SAID 'WELL YOU'RE ON THE RWY NOW; WHERE ARE YOU EXITING?' I RESPONDED TXWY F; AND APOLOGIZED. HE DIDN'T SEEM UPSET AND NO ACFT WERE LNDG OR TAKING OFF ON RWY 10R; NO ACFT WAS INCONVENIENCED AND SAFETY WAS NOT COMPROMISED. I FEEL THAT THE CTLR SHOULD HAVE BEEN MORE ACCOMMODATING WHEN THERE WAS OBVIOUS INDECISION IN MY VOICE AND HESITANCE TO CROSS THE RWY WITHOUT KNOWING EXACTLY WHERE I WAS TO GO.