NO..it is not just short free verse..
It is completely different than free verse.
1. haiku in tone it is objective and most free verse is subjective
2. haiku has a definite structure..
A. haiku is about a MOMENT in time
B. 3 lines
C. 2 of the 3 lines [or parts] are joined CONCEPTUALLY[they are about the same topic and GRAMMATICALLY [if placed on a single line they would comprise 1 thought.]
D. A single image/phrase/fragment or topic [which may or may not be a complete thought] finishes the haiku. This input adds more sensory information to the MOMENT.
* In Modern/Contemporary/Western haiku a season word is not necessary & man is included more often
Free Verse has no definitive structure
A. Free Verse uses ANY poetic device it wants [metaphor, simile, personification, onomanopepoea, oxymoron's, alliteration ..] haiku uses almost none!
B. Free Verse can relate any or many or all periods of TIME. haiku is only about a moment.
C. Free Verse is almost totally SUBJECTIVE, it contains personal judgment, analytical thinking, FLIGHTS OF FANCY!
Here is a verse I wrote perhaps a year and a half ago and labeled haiku
Ghostin’ White
The wind chased dry snow
swirled, slipped, and sledded entranced
ghost dancing the pavement.
*This is PURE Free Verse. It is NOT a haiku.
*The image is SUBJECTIVE, fanciful, it involves MANY MINUTES
[for there is MUCH action!] swirling, slipping, sledding, dancing
Let me try to rebirth it as a haiku..for you to see the difference

the wind
swirls the dry snow on the walk --
frozen clothesline
* One MOMENT, 1 action, 1 topic WIND and 1 added bit of input
haiku
Why not look back on your old writes and reform the ones LABELED haiku into haiku.
This DOES NOT mean those old writes were BAD, I would bet the farm many, many of them are exquiste! BUT haiku is NOT short Free Verse.
If you want help reforming or rebirthing them post one here in the comment section and we can play!