Sounds like you need a transmission diagnostic from someone you can trust not to sell you a rebuilt that you don't need yet. I found a trustworthy trans shop near me by going to car talk .com. They did car repair help radio talk shows for decades, Click & Clack, noisy tappets. Here is a link to find a good shop near you https://www.cartalk.com/mechanics-files just put in your location and find a good shop from reviews. A trans shop can plug into your trans and see exactly what the problem is, replace the switch, sensor whatever and get you going. You just need to find a trustworthy local trans shop that won't cheat you. Cartalk has good repair archives online that you would like to read. Is great learning material.