Flame Test Spectrograms Not Lining Up With Reality
The first step you can take to make the spectral bands narrow is to reduce the slit width. It is slightly wide at this moment. We are not sure where you were looking for wavelengths? In the compiled tables in handbooks or schematic diagrams on the web, the emission wavelengths are listed for the excited atoms using very high temperature flames using air acetylene, or nitrous oxide acetylene flames. The ordinary flame temperatures in a laboratory are too low to electronically excite the atoms of any other element other than alkali metals. For Li, Na, K, Cs, you would see a line spectrum for each element (one or two lines). For potassium is extremely difficult to see the far red wavelengths (the resonance wavelengths listed in tables) until and unless your eyes are sensitive to red. The flame colors Ca, Ba, Sr, Cu are usually due to molecular compounds of these metals in the ordinary flames. 

The key point is that the flame temperature is too low to see the line spectra you were expecting. However, if you look at discharge tubes, then you can do a good comparison.