Internet recovery of 2015 MacBook Pro fails due to unavailability of Yosemite
You are correct - the issue you have is that Yosemite is not in your Purchased history.

With your MBP and its history, you should have three options open to you:


commandR to reinstall the latest macOS that was installed on your Mac, without upgrading to a later version 
optioncommandR to upgrade to the latest macOS that is compatible with your Mac
shiftoptioncommandR to reinstall the macOS that came with your Mac, or the version closest to it that is still available1


1 That third option is a new option only available when macOS Sierra 10.12.4 or above has been installed.

Obviously we can't be 100% sure what version of macOS was pre-installed when new, but it most likely would have been Yosemite 10.10.2.

I would try rebooting your MBP again using each of the above combinations one by one to test what happens, as it may be you can successfully reinstall macOS with one of them.

Let me know how you go.