You used 623C at a bad time, preforming 214B/C or 236B/C would've extended the combo you were doing that time. Timing your DP's wrong can be dangerous and will give your opponent and advantage, such as Lambda with her 5C (IMO, it's annoying).
Don't execute C again after 2C once an opponent executes an air recovery, it will lead to the combo ending unnaturally. You also shouldn't preform 6C© while the opponent is preparing their attack, such as Lambda's 632146D distortion. You should also be aware that one way to cheat yourself out of Lambda's 5C is by attacking her using a trick maneuver, such as jumping over her and attacking with j.5C©, or attacking her from behind to trick her. Preforming attacks such as Tsubaki's 3C during Lambda's 5C is dangerous, as the bullets from it do not affect Lambda when countered.
I am trying to help you as much as I can, and I hope what I said in mind helps.