Hi Eileen
I have an 1855 BC it says 2 boys living 1girl deceased, not clear number of children she had.
So you can account for two of the mentioned children? The girl should be quite straightforward (well, OK, maybe not, as death is pre-1855 by the looks of things). As for the boys, being two of them may make it more difficult to work out - is the 1855 birth a boy?
My thoughts would be to keep an open mind on this one and just try to find out what you can. 1844 - 1855 with no children does seem a big gap, as you noted... what was the father's occupation? Could it have been something which kept him away from home for long periods? Other thought, if he was likely to be at home may be that there were perhpas miscarriages or maybe still births during that period. What is happening on the census returns for 1851 and 61 children-wise with this family?
Good to see you are still working away at it!!
Best wishes
Lesley