If your transaction is showing up on block explorers like blockchain.com, blockcypher, blockchair etc... then rebroadcasting is generally not necessary, especially if the transaction is less than 3 days old and even then, it is more likely to hang around for up to 14 days on a lot of nodes.
The "old" default mempool expiry time was 72 hours (3 days)... but because of incidents of the mempool getting "flooded", there were times when 3 days wasn't enough and transactions were being dropped and it was causing a lot of confusion, so the default mempool expiry time was pushed out to 14 days.
Of course, this is just the "default" setting... and individual "nodes" are free to set whatever they like... but generally speaking, the vast majority of nodes will hold your transaction for a minimum of 3 days.
Rebroadcasting is really only needed if your transaction is no longer found on block explorers... once that starts to occur, then rebroadcasting is not only helpful, but probably necessary.
As for OPs transaction, sadly... it looks like they walked into a "Bitcoin price increase", that naturally comes with increased network activity as people move Bitcoin around to buy/sell etc. The graphs on https://jochen-hoenicke.de/queue/#0,24h really show that quite well... currently (@0130 UTC 2019-04-15), the mempool is up over 8 megabytes (around 8 blocks worth)... and OPs fee puts their transaction in the bottom 2/3's of that pile.
TL/DR; your transaction is STILL going to take a while to confirm!
somehow I completely missed your post, I am so sorry.
Thank you for a very clear and thorough explanation!!!!