Q: Can you please help me fix my jumpy, erratic trackpad?

See if cleaning the trackpad helps.

Cleaning your Apple products - Apple Support

Also see:

If your pointer is jumpy when you use a trackpad, Magic Trackpad, or Magic Mouse - Apple Support

Also, see if the battery is swollen. If swollen it can apple force to the backside of the trackpad causing problems.

... and if the erratic behavior still does not go away, your trackpad may need to be replaced. You appointment at the Genius Bar at an Apple store for an evaluation is free, in warranty or out.

If the trackpad needs to be replaced, or any other service is recommended, you are under no obligation to have Apple perform the service. Apple's fees for services are all flat rate, no surprises.

Maybe. As Grant said,

Make an appointment at the Genius Bar of an Apple store, evaluation is free.

  Apple Retail Store - Genius Bar

https://www.apple.com/retail/geniusbar/