You never said this nor have you told us what you have tried.
If you’ve burnt up three months of your life, you’ve got some significant skin in the game.
First thing, get a known good node, something that’s already been tried & tested, to make sure your gateway is good.
Second, go to a known good gateway to try your node.
Third, build something simpler with off the shelf components - Arduino + UART based radio module. Or if you still have some patience left, Arduino + a radio chip via SPI like https://github.com/descartes/Arduino-LMIC-example which I can help with in detail.
I did ask a question about your regional settings so I could answer your question about SF10 vs SF12 and the data rates but you haven’t answered. Where in the world are you?
And exactly how far away from the gateway do you want your device?
I can get 100km LoS out of SF11 20.8k DR on 433MHz with the transmitter using a 16cm piece of wire as an antenna and the base station with a mag mount aerial, so a few km with well placed kit is entirely possible on the ground.