How do I calculate my service time for retirement?

Here is my $.02 for you .
I have been where you are at some time long ago. Thinking if I would pull all my pennies, ( retirement points) I could retire more "quickerly"!
If your situation is such that you are wanting to change it at all costs, I am truly sorry for you. Hold on it will get better.
Here is my plug nickel for you; start trying to focus on your 2nd day of retirement, and what it will take to get there. Start asking the questions of the future, like:
Where are you going to live. Start talking to relator's.
What job are you going to seek or take Get your resume' together
Where is the kids going to school? Will the schools' report cards influence your house choice?
By look past the present to the future make your day to day easier?
When we were about 18 months out to retirement we started looking at income streams that the farm will produce and the cost of the equipment cost to so these ideas. Did we make some mistakes on the plans? OH HAIL yes.
Now are almost 10 years of retirement, we don't have a vineyard or an mixed fruit orchard, or a bunch of rotating butchering chickens , or a green house full of vegs.
What we do have is: more cow/calves that I can count on ONE hand, getting more eggs than we can eat, more bee hives than I can keep up with, and more honey than we can sell or eat. got a tractor that has a HYD leak and needs an oil change a year ago, a steer that need butchering.
And a maturing family that likes where we are.

One more thing ask your wife and then your kids where and what they want to be doing to 2-3 years.

Good Luck soon to be VET.

HtH
Tim

The DoD FMR has this in detail, but in brief:
Your UTAs, ATAs, RMAs, and AT/ADT days count as "days" towards retirement; correspondence course and membership points do not. So take your retirement points sheet, subtract those points and divide the remainder by 365 to determine how many years of creditable service towards an active duty retirement that you have.

Start with the S1 but it'll end up at HRC. The will need your Reserve and NG discharge documents. This will show days of active federal service while you were in. I know for the Guard, they will only count the days you were on active federal service, ie BCT, AIT, Deployments. Not sure about your reserve time. The will calculate the days of active service and adjust your Active duty service date to include those days. It took a while for mine to be fixed, so be patient, but diligent. It's your paperwork and personnel has be known to drag feet.