If I understand you correctly, when you look at form 8885 on your original return, there is no dollar amount at the bottom on line 5.
If so, then you do not have to amend the return in the sense that your tax was done incorrectly. The IRS computers may eventually be curious about you filing an 8885 but were never authorized by the government to receive the credit, but this may be unlikely.
Just write down what you did and include it with your 2018 tax file so that in case the IRS ever writes you, you will know the answer. Note that if you get such a letter that when you reply that you didn't mean to file it and would they delete it, that the agent running the letter audit (that's what these letters are called) may just offer to remove the form (so no amendment needed). Let the agent guide you, if it ever comes up.
