very confusing -- here's your fool proof method -- Whatever you set your stitch length to, sew enough stitches to be measured by one inch. [simple? -- right!] use a measuring tool [preferably a ruler] & COUNT the stitches that were sewn in that one inch, now you know how many stitches per inch that setting sews!!!
if all else fails, read the instruction booklet that came with your machine!!!
if you wanted your machine to stop at 2.75 inches, i would measure the fabric & mark where 2.75 is!! [provided this is a straight line...]
hope this makes sense and helps!