It sounds like you did not measure the voltage of a white LED. It is much more than 2V, probably between 2.8V and 3.5V. You said LEDs in plural. If you connect a bunch of white LEDs in parallel then since they all have different voltages, the LED with the lowest voltage will take all the current and quickly burn out, followed by the LED with the next low voltage and it will burn out, followed by ... etc. The voltage of an LED drops as it gets warm which makes it draw more current which makes it warmer which makes it draw more current which makes it... have thermal runaway and it goes POOF!
Buy thousands of white LEDs, then test and sort them into piles with the same voltage. They do that in China to make cheap white LED flashlights. Hey, use the matched LEDs from a flashlight.
Why not connect a few LEDs in series then your current limiting resistor does not waste a lot of power making heat.
Four 3.5V white LEDs need 14V then a resistor can be in series to limit the current with 3V across it
if the LEDs are 2.8V then four need 11.2V and your current limiting resistor will have 17V - 11.2V= 5.8V across it.
Four LEDs and a resistor are a string. Connect as many strings to the 17V as you want.