We have done what you are planning to do. It will be 18 months at the end of next week since we retired. I understand your concerns, we had much of the same ones, particularly DW, who is fearful that the benefits that we rely upon will be diluted in the future. I scoffed at this at first, but after last year's retiree pay COLA challenge, I'm not so sure. There are no guarantees, but we have no regrets taking the plunge.
We have done what we can to mitigate the risk and what we've done falls in line with much of the advice given on this thread. We have socked away funds in TIRAs, Roths, TSP, and taxable accounts to cover the unknown and big emergencies. At O6, we were able to save about half of my pay every month so the funds increased rapidly after that point. I didn't stay to 30 as I didn't want to live on the East Coast anymore, but financially, it wasn't necessary to stay and it gave us the freedom to leave the Service and be grateful for the memories and opportunities that Service life had provided.
Our lifestyle fits easily within the retired pay, but keeping your cash flow positive and expenses low is key. Here in Colorado, it's easy. If you retire in the D.C. area or a higher cost of living area it could be a challenge.