First Wort Hopping Questions

I've recently discovered home brewing and am exploring new techniques such as First Wort hopping. I've brewed several batches that are still conditioning, some of which the only hop addition is first wort.
I have only tasted one, un-carbonated and it seems too low on the bitterness although the
Brewing program I use (Brewersfriend.com) calculates the IBU's at 46 to an OG 1.057. I'm still unsure as to the final result.
Is anyone else doing this or am I just making poor decisions?

I have made a few FWH only beers. This works good on styles that typically aren't hop forward such as cream & blonde ales.

Because of chemical changes that happen as the FWH steep, it tastes less bitter even though it measures very slightly more than an equivalent 60 min. addition.