Yes, you have done brilliantly! And some people just naturally have apparently-random large weight fluctuations over shorter periods of time anyway, so having to stay within a 6lb range sounds very tough to me!

FWIW AFAIK there is some suggestion that it is easier to put on weight if you recently lost it, so perhaps such upward swings will become less common over time, if that's any consolation. You have still done really well, though.