What am I doing wrong in order to not achieve this effect?

Hello. I am attempting to make a similar background to the attached photo below. It was found on Pinterest, and that is as far I found for the original artist, besides it being based off a Taylor Swift song. 

My trouble is coming with the effects on the heart. I have used Gaussian Blur as well as Feather, and cannot seem to get the same blurred, soft edges as the source picture. Instead, the entire shape is transformed evenly, and I am unsure how to have it focus on the edge/strokes specifically. 

I've attached the source (Red heart with text) and my current edit (green, no words) for reference. 

I'd appreciate any tips or referral to tutorials, as I am not able to articulate what it is I'm looking for. Thank you!