I completely feel you, because shortly after I dove into fretless, I decided to go for broke and buy a Carvin 6-string fretless.
My friend, the first 2-3 months were a complete disaster! I only played the Carvin at home until I got used to it. The biggest adjustment was in my hand position for picking. I basically use only 3 techniques now - over the bridge pickup, over the neck pickup, and pivoting from beneath the strings to pluck with my thumb. Each has a different attack and overall tone, so I can really fine-tune the sounds coming out of the bass that way.
A good tip that I've seen mentioned above multiple times is to start getting used to a moving pivot. Learn what positions work for standard low end bass lines, for walking lines, for solos, for slap and pop, for thumb picking, etc. Spend your time working hard at transitioning between the various pivot locations smoothly.
While you do it, be sure to work up your vibrato with your left hand. That's often overlooked by new fretless players, and it will help your intonation immensely. Sometimes you want to hit right on the note, and sometimes it's better to sort of float over it.
Good luck!