Trying for baby. I late to make a baby?

So I have been tracking my ovulution cycle based on calendar plus ovulution strips...I have fairly regular period with cycle average 27.5 days..I tried ovulution strips on days overlapping with my predicted fertile window as per calendar...2 days the color of 'T' showed a gradual progression from faint pink to darker pink, though way less than 'C' as on the tester strip...As per the information on the box + online search it meant my ovulution days are still to start..On 3rd day when I was expecting better results, the pink color completely vanished to my surprise...I tried testing for few more days but same result.. I was using 'I know' Ovulution Box...Does ovulution predictors work? I missed my fertile window without understanding what went wrong... I got late testing it??..or did it happen very late? Should I buy another brand of ovulution strips? What should be the way ahead..please guide...Also another psychological problem I am facing is the age factor...M I late to make a baby?