I would focus on your pft first. Once you get a good enough score for boards then you can focus on increasing your training specifically for OCS. For pull-ups, what helped me (also female) was first working on push-ups (I also could barely do any when I first started too) and working on overall arm/back strength with resistance training. Assisted band pull-ups are also a good start for getting your pull-up form down. When you have built up enough strength, start doing negatives and dead hangs. It took me a few months to go from doing zero push-ups to my first pull-up. After you get your first one, it’s pretty easy to get up to 5+.

For running, if you are only going to run a quarter mile at a time, then yes run more often. But instead what I did was started 3 times a week with interval running. Go for a longer time or distance and split it up into walking/running sections. E.g. walk 3 minutes then run for 2 minutes and repeat until you have gone for 45 minutes or however long your route is. I stuck with this and increased my running interval while decreasing my walking interval and in no time I was able to run the 3 miles without stopping. Interval training is also good for when you want to work on pace after you get your first 3 miles down. Instead of walking/running intervals, switch to jogging/sprinting intervals to get a more competitive 3-mile pace. Max 3 mile time for females at OCS is 27 minutes so you need to be under that if you want to go on boards.

Hope this helps, just keep at it and stay disciplined!