You should have the lastest... They just released 2 updates since ur last one...If u didn't get it,go to sammobile support page they have all the latest u can download using smart switch
I have told this so many times, everyone who has Unlocked on T-Mobile you need to remove the sim card and insert another sim card even if non active sim card for you to get the update. T-Mobile is delaying the certification request from samsung and samsung is releasing the update except T-Mobile. Again, You need to remove the sim card and insert another sim card to update. You can try to remove the sim card and update if you cant then you need to put another sim card even if non active.
Confirmed RedDragon's suggestion to use a non-active SIM card to download updates. I used a Verizon SIM and was able to successfully download the update. I'll add that you have to wait for "updating your device status" to complete. "Download and install" will remain grayed out until that is complete. I now have the July update on an unlocked S10!!!