what are expected ranges for playing in 5/10 to 8/16 limit 6 handed

[johnep]

greetings, 1st time posting

i tend to play alot of 5/10 to 8/16 6 handed limit hold em. Im curious as what to what to expect for the ups and downs. I started w $300, got it up to $3700, down to $2600, back over $4000, and now Im at $3300. (this is within a 3 week span). Also at what point should I feel confident that Im playin correct poker and not just getting lucky.

kind regards
yds