is it like 'infinite missions' ?

or does it end (ever) ?

right now it feels more like, I keep reporting back to them and they keep sending me back again

infinite. they were designed to help level the character early game.

Semper Invicta officially ends once you've done one Cleansing the Commonwealth and one Quartermastery quest with Rhys and Haylen.

After that, the quests are never-ending, but a good way to get XP, caps, and to have an excuse to explore new locations.

I keep doing these quest hoping to move on with BOS story line but I don't know how to progress.... It's getting old.

In order to continue the BoS story, you first have to complete the main story quest "Reunions", which you get after rescuing Nick Valentine. After "Reunions", the Prydwen arrives in the Commonwealth and you have to tune into the radio to get a message from Paladin Danse. From there, he takes you to the Prydwen and you officially become a member of the BoS and are able to truly begin their story.

I hope that helps.

Thank you! I'll get on that tomorrow. I thought if I kept running their errands it would eventually progress. Thanks a lot!

im just as guilty. prolly did about 30 quest before moving on. =P