It's a little small for OWB honestly, but DeSantis and Galco both make good options. You should check out the new LC9S, it is a sweet shooter and the new trigger is great. I'm a total Glock fan and have been for years. Carry a Glock 19 or 32 as my primary pistol for past decade, but I didn't like the G43. Was super excited when first came out, thought it would be the perfect auxiliary/backup carry pistol but I just didn't shoot it well. Ended up selling it because I have too many other nice micro 9mm that I shoot and prefer. My favorite little slim 9 is the M&P Shield. That's my current aux pistol. Before that it was my Keltec P11 or Glock 26. I also have a Sig 938 and recently purchased LC9S and love both of those as well, but the Shield just feels best in hand and I run it the fastest so that was given the carry nod.
Funny thing about the new LC9S, I don't ever own or carry .380s and pretty much consider it a subpar defensive caliber but the improvement on the new LC9S was so good that I went out and bought the new LCP 2 as well! I got it solely as a pocket gun for gym shorts/sweat pants for those times where I'm running out to the mail box before getting dressed, or going out into the yard with my dogs etc and I don't want to have my normal carry rigs on at that time. For the few instances like that I feel the LCP is a great option and .380 beats my fists or a tactical folder in the chance that I need to defend myself in those instances. I also will be taking it to the range some too because it is a fun little shooter just like the LC9S with Rugers new triggers.
Anyway congrats on the new purchase, I love Glocks and always will and I think if you shoot it well that 43 will serve you as a great CCW pistol. FYI in my experience it does best with 124/147 grain ammo and prefers a more stout load to a weak load. Initial break in of my 43 saw a few mis-feeds but only with 115gr Winchester White box, 124 American Eagle (Federal), 147 Aguilla and all the 124/147 JHP defensive loads I ever fired all functioned 100%. The most accurate carry loads for me were Federal HST 124 +P, 147 +P, Gold Dot 147, Golden Sabre Bonded 124 +P. Overall though I was not very good with this baby Glock , so I decided the 26 was the smallest Glock I want to keep.