You can have 2 weeks of back pain a long time ago and get rejected for that alone? That can happen from sitting in one of those garbage $5 office chairs 10 hours a day.That’s been the theme with many N3M disqualifications. Best of luck with other services and hope it works out!!
You should take a good look at the Air Force. Very good for civil engineering and really anything technical/engineering related.So looks like I have to join a different service, or even go to the space force
Worst comes to worst, if you like running and you can show that 2 weeks of back pain a long time ago isn't an issue, Marines will pretty much take you. And considering you're competitive for Navy DCO, you're overqualified for the Marine Corps. You may be a bit too "old" though unless you can get an age waiver. You just got to grind through 3 months OCS and 6 months TBS...