I dont expect any amount of logic to convince you... but generally (this is from wikipedia) the properties of fascism are:
dictatorial leader
centralized autocracy
militarism
forcible suppression of opposition
I see the left expressing these things in spades, at least from the far-left which dominates the left scene (I myself am centrist-left and wouldnt include myself in this, or any of the small-minority centrist-lefts)
dictorial leader is clear, the DNC left routinely expresses the idea that any choice other than them is unacceptable, and supporting even third-party candidates is usually meat with aggressive abuse from many on the left.
centralized autocracy - this goes hand in hand with the last point
militarism - Absolutely, both sides have done little to nothing to reduce our overwhelming waste on military funding.
forcible suppress of opposition - this one is the most evident for me. We have seen it in the violent riots at universities where right-wing people intend to speak to the point of damaging equipment or threatening lives all to suppress opposition. Also botht he right and the left actively suppress third-parties.