If you are counting 15 speakers, then you did count 19 speakers as stated correctly. Trust me, you are not the first and last to ask this. Their is a long list in front of you who did.
You have 5 coaxial speakers. Coaxial speakers count as 2, since it is 2 drivers consisting of a midbass/midrange driver and a hi-end (tweeter) driver. This is how the audio trade across all fields go by.
Best for now.
Laredo X, Trail Rated, QTii, Sele-Terrian, Quadra Lift, Off-Road Adventure Package ii, Nokian Rotiva AT, Tow, AFE CAI, DiabloSport inTune 1000-DCX, Custom Sound System ( HAT speakers, JLAudio , Pioneer , JBL MS-8 & RF 3.sixty.3 -- see the writeup link below for more details)