Yes indeed! Been putting it off for too long but it's the time to make a detailed schematic.
I am now using MOSFET IRF520N for switching LEDs and my problems seems to went away, no more display errors.
Now, the only thing that i am not sure about are resistors on MOSFET, in some schematics i see a resistor (usually 1k) is connected between Arduino PIN and GATE pin on MOSFET and somewhere 10k resistor connected between Arduino PIN to GATE and GND... to prevent floating pin state because of high impendence, which as far as i know is a problem on INPUT pins and not on OUTPUTs as in this case...
apart from that, my rig is 99% finished!