Turn on all of your accessories in the interior of your vehicle that you can control from the drivers's seat. Blowers on high, radio on, headlights on bright, etc and see if they dim when you try to start the vehicle. If they do not dim or slow, then your battery is okay and you should start looking at the starter.
If you don't mind me asking, where are you located? Most automotive part stores in the US will test starters for free.
Let me know what you find or if there is any more information that I can find for you.
Sunday, January 20th, 2019 AT 12:10 PM