Hi, Welcome to RootsChat.
They were married on 14 Jul 1845 at Llechcynfarwy Church:
Robert Thomas, f, b, Shoemaker of Llanerchymedd, son of William Thomas, labourer and Ann Jones, f, s, Llanerchymedd, dau. of Owen Jones. labourer. Findmypast has the image of the marriage certificate (but the parish is wrongly transcribed as Llanynghenedl). They both signed by mark, the witnesses were (unclear?) Jones and Hugh Prichard.
I have found details from the birth registrations of some of the children you mention, all registerd with father Robert Thomas, mother Ann Jones and born at Llanerchymedd:
Ann - 30 Apr 1846; William - 29 Nov 1848; Mary - 14 Mar 1851; John - 8 Dec 1853; Robert - 20 Mar 1856; Ellen - 3 Jun 1862; Owen - 12 Oct 1864; Catherine - 29 Dec 1867.
I will look again for the two later children.
Do you already have some census information? Is there anything specific you wish to know?