Bike front derailleur

I bought a bike from EBay. It has decent components, but they seem mashed together incompatibly. My front derailleur doesn’t shift properly.

I tried adjusting the front derailleur, with little success. The clearance to the big ring is always than 1mm (too little).

A mechanic told me that my front derailleur is for a double-ring crankset, and therefore incompatible with my triple-ring. However, I’m not sure whether the mechanic is right. The derailleur is a Shimano FD-2203, the manual of which suggests it can work with a triple-ring.

Here are the components:

There is a mixture of different Shimano series here: 2203, 6600, 5600.

From the manuals, the main “incompatibilities” I noticed are:

The front derailleur looks like the impostor, so maybe I should replace that - but what with?

The manual for the FD-5600 wants 20 gears, so that doesn’t work.

The manual for the FD-5603, suggested by the shifters, wants:

Is this the cause of my problems?

Here is a photo of the front derailleur:

front derailleur

I wrote this because I felt like it. This post is not associated with my employer.