Dalrymps - I think the dr is just trying to be cautious, although 6-7lb is not that small.
There are 2 main types of small baby, apart from prems, firstly the 'small for dates' baby which really just means that you have grown a small baby which has had normal growth throughout pregnancy. This would probably be the category you come into and this is ok.
The other type is an intra uterine growth restricted or IUGR baby, which is a baby which has had reduced amounts of nutrients, most often due to placental reasons, such as PET, placental insufficiency, diabetes etc and is in the lowest 10% of the growth chart.
These babies are at risk in labour and late pregnancy because they do not have good reserves to withstand a long labour, so can sometimes get quite stressed with in labour.
If your consultant was concerned that you fit into the latter group, he would not have let you go home, let alone waiting till 10 days over, so he's obviously not that worried, but if you are going in today, I would suggest asking for a scan to check dopplers and fetal wellbeing, with an estimated fetal weight. If this is all ok, I dont see a problem with waiting until the 42 weeks.
As Lulu would say - get going with the sex, nipple stim etc.......