Shifting slippage

Yes it is a V6. I haven't checked tranny fluid lately I will check but I know I have zero leakage as never a spot under the car anywhere. I have a code reader I will throw on tonight, but I do know there is no check engine light.

Put code reader on it, no codes. Had tranny flush done to no avail but it was worth a try, Did find when I check fluid level before service it was below second dot. Strange as it has never leaked. Just drove it to home depot and twice from a stop started to give it gas and no forward moevment. Do it long enough and the service light comes on. Once the car is parked and then restarted the service light goes out. Also, note that when this occurs I was able to manually shift it into low and then get moving then shifting manually back up through gears to drive. If I were to shift to neutral and then back to drive nothing but shifting to low seemed to work. Any ideas would help?

Just to let you know. Took it to show as if it was transmission I did not want to replace. Then I remembered I had an extended warranty. Turns out transmission was bad and had to replace. Best extended warranty I ever purchased. Paid $1790 for warranty nad so far they have replaced the a/c compressor and now the tranny.

Thanks for your help