In my opinion, unless it was a super tough placement you are better off just pulling it out and repeating it. These usually tend to still give a positive test dose despite negative aspiration after pulling it back. If it doesn't give a positive test dose, it is likely to be patchy. Very few successes in my hands in salvaging these catheters. If I want to rely on a catheter I will replace it.
Don't thread it 6-7 cm into the space. 4-5 cm is enough. The more you thread the catheter, the more likely it is that the catheter will run into a blood vessel.
If the patient is complaining of pain as you proceed with your LOR technique reassess your midline. If you are in the midline and have given local, they shouldn't be having sharp pain. If you are off midline you are more likely to run into a blood vessel. If you see blood in your epidural needle, you are likely off midline. It doesn't have to be a huge amount -- just a couple of millimeters.
Generally speaking, attention to good technique avoids most problems. When in doubt, pull it out and redo it.