Trying to run two motors simultaneously using millis()

I'm willing to help. But only under one condition:

You post a pretty detailed description of the functionality.

The following bolded capital letters are not meant as "shouting"
It is just a very high emphasising

functionality means

NO CODE ! JUST NORMAL WORDS

I made the experience that some users always try to talk about details of coding.
As long as other users do not have the "big picture" it is hard to give good advice.

This is the reason to post a normal worded description of the whole project and a normal worded description of the wanted functionality

There are two diametral different approaches to code:
.

  1. linear sequence

  2. circular repeating through void loop()

circular repeating means void loop() is looping fast.
As fast as possible. Things that should only happen from time to time or at a low frequency
are executed only from time to time with non-blocking timing

You have to understand circular-repeating in combination with non-blocking timing first
especially the difference between linear sequence using delay()
and
circular-repeating which

totally avoids delay()

through non-blocking timing

edit: in post #7 I expanded my non-blocking timing tutorial with a new kind of visualisation how non-blocking timing works

repeat doing things at different frequencies

best regards Stefan