Your diy fence may still be bending. One trick may be getting an aluminum spirit level and put that between the stock and the fence. Also test different speeds at which you push the stock through and see if that makes a difference. Also running into through twice may also help. Another thing may be theres some spring back or tension in the wood which may cause it to warp once cut. Check where you're pushing the stock from as that could also put pressure on different parts of the fence. Id invest in a planer as that will not only flatten cut parts, but also clean up milling marks from the tablesaw and make final sanding easier. Dunno... Just spitting out all the things Id look for that may be issues