Relapsed during flatline

Hey, just relax, so you slipped no problem there, just learn from it and move on, what were your doing at the time (browsing the web, procrastinating etc.), what were you feeling (sad, angry etc.) and also what actions preceeded it (closing your door and isolating, touching yourself etc.). If you start to learn what preceeds a slip and the triggers that get your to that point, you will be able to stop them in their tracks, maybe temporarily until another day but that's fine, you have to come at this one day at a time. Stop worrying about where you're going to get to, you will get there but only by getting through the current day. You needn't be 1 week, 1 month or 1 year porn free today!
Now most importantly a flatline isn't going to disappear in any alloted time so you have to be patient, it could take a few days, a few weeks, a few months or upwards of a year, but that's natural. You have put your brain through the wringer here, it's not going to heal over night, there's a lot of rewiring being done in your brain everyday, and the longer you go the more rewiring will be done, but patience is the key. Sex and sexuality are not everything so just enjoy your days and push it aside, and most importantly do not worry, worry will only lead to peeking to see if it's just gone forever.
On the matter of penis size just chill, it's just a penis, it will return to normal, but ultimately it's fine, there will be no real change to it unless you keep abusing it with the five finger death grip, so keep calm, it'll be fine.
I hope this helps friend, good luck!