Sounds like my brick wall.
Another suggestion-collect death records of any elder in your family. Also collect death records of anyone regardless of age. Informants names are listed-sometimes address'. For the informants, research that persons family line. I noticed for a long time MEN were the informants on death certificates for family even though the wife or a child was living. Then cross reference on the census where these people lived at the time your parents lived. I can't wait to see what the 1940 census will tell me. Sometimes you stumble on information. Sometimes you may never know the answer. Parents were not important to slaveholders for children, unless they were trying to keep their 'stock' strong'. That's the way it was then. Get a good stud to build up the work force. Then some slaveholders bred their own stock themselves. Everything about our families is not in writing. You kind of have to put one set of ancestors aside for awhile until you look into something else. There are so many sad stories about our origins. And would you believe some of it is still going on right now--children being born into families- no father or mother stepping up. Foster Care!!! Don't give up. Take a rest. Go to an out of town family genealogy conference. Take some of those classes. Then come back and start again. Family Genealogy Classes Work. There are people there going through the same thing you are. AND I have seen 'cousins' who did not know each other meet for the first time, not knowing they were related until someone ASKED A QUESTION.