You don't need a specific organ to have a reaction to chemical signals.

Yes..... you do? That would be like saying you don't need a nose to smell, or taste buds to taste.

pheromone is just a chemical the body creates, and an external body responds to

No. Pheromones are chemical messages that trigger specific behaviour or developmental changes in an external body.

That response can be due to smell, taste or even touch. No special organ is needed for any of those.

Smells and associations attached to smell are not the same thing as pheromones. In certain mammals and reptiles pheromones are received by the vomeronasal organ.