Thank you for the translation! Though I do have a comment:
I'm fairly certain that this is chapter 17 of the official serialization. I don't know how you assumed this to be chapter 6 (maybe it's the pixiv comics or the doujins, but even then, it doesn't say it's chapter 6). As for why it's chapter 17, it's because the official serialization follows the same order as the webcomic (plus, I read this chapter last week when it was free to read on the official site). The official serialization is currently on chapter 19, which is the same as chapter 21 of the webcomic.
To make it short, I recommend separating the previous chapters into their own chapter, as the pixiv comic is not a good source for chapter numbering, to these being collections of previous chapters (that were published on Twitter). So either:
1. Follow the Twitter chapter numbering (this chapter would be considered as chapter 19)
or
2. Follow the official serialization (this chapter would be considered as chapter 17)
Sources:
Twitter Chapter Count (originally published on Twitter): https://twitter.com/i/events/1012164438772756481
Official Serialization (Official chapter count): https://storia.takeshobo.co.jp/manga/university_firstlover/
pixiv Chapter Count (published after Twitter as collections of the Twitter webcomic, although it eventually was released simultaneously as the Twitter webcomic): https://www.pixiv.net/user/265720/series/48548?p=4
I'm even fine with helping with the chapter numbering if you do wish to follow my advice.
I hope I didn't sound too condescending. Anyways, thank you for the translation!