I suspect the OPR records either weren't made or have not survived for these births prior to 1855. You're fortunate in that you have a very narrow window in which he must have been born so that your age estimate has got to be close. By searching the IGI you learn that this couple continued to stay in the Bridgeton area for awhile and this is a list of subsequent births to them:
JOHN TAYLOR
Birth: 31 JUL 1855 Bridgeton, Glasgow, Lanark, Scotland
RACHEL TAYLOR
Birth: 27 FEB 1857 Bridgeton, Glasgow, Lanark, Scotland
DANIEL TAYLOR
Birth: 29 SEP 1858 Bridgeton, Glasgow, Lanark, Scotland
HUGH TAYLOR
Birth: 11 MAY 1860 Bridgeton, Glasgow, Lanark, Scotland
MARY URE TAYLOR
Birth: 29 JUL 1861 Bridgeton, Glasgow, Lanark, Scotland
HUGH TAYLOR
Birth: 03 APR 1863 Bridgeton, Glasgow, Lanark, Scotland
ALEXANDER TAYLOR
Birth: 18 JUN 1866 Calton, Glasgow, Lanark, Scotland
MARY URE TAYLOR
Birth: 02 APR 1868 Calton, Glasgow, Lanark, Scotland
If you view the BC of John recorded in 1855 on Scotlands People it will contain a reference to how many children previously born to this couple that are living or dead in 1855. Unfortunately no names will be given but you can further estimate from this if you have accounted for all the births you think you are missing. Hope this makes sense?
Best wishes
Jean