The pressure for my water keeps going so low that I have no water. It happens when I'm
Using a lot of water like a few loads of laundry in a row etc. I push a button to reset
The pump & then hold a lever on the pressure tank till the pressure comes up & it's OK
Again. Could this be that the pump is going or is it something else? This last time I did it today I thought it wasn't going to work, it was kind of struggling to get going. Please help me because I have a geothermal system & I cannot use it now at all.

It could be the pump, or it could be that the well is running dry. You best bet may to get a well tech or plumber out to see exactly what is happening at the well.