Go with off the shelf. You'll get something far better that you can build yourself, and if you need something custom, you'll have a much clearer idea what your

Go with off the shelf. You'll get something far better that you can build yourself, and if you need something custom, you'll have a much clearer idea what your analysis is missing. Writing to Google Analytics, Amplitude, Mixpanel (all of which have free tiers) or equivalent all should handle your case well.