Just for the heck of it I pulled up Pathbuilder and did a Gnome with: 14, 14, 15, 12, 12, 15 after racials applied. If you don't want extra skill points or Wis (raging does help with Will saves, obviously) then I'd go with a 10 in one of those and have your CON start at a 16. At level 1 with a Greatsword, for example, when raging you'll be at a +6 to hit and do 1d10+6 damage. That's honestly not bad at all. At level 5, just for example, with a MW weapon you'll be at +11 to hit and do 1d10+6, but since of course you'll be Power Attacking it'll be +9 to hit and 1d10+12 without anything else like Furious Focus, Reckless Abandon (why not go Primalist + Steelblood?), or bloodlines.
I theorycrafted a Halfling Bloodrager and the initial STR hit REALLY isn't a big deal in my opinion. If you're thinking about going Bloodrider, then being small REALLY doesn't matter as much (at least from level 5). You'll have a 1d6 lance with a +4 or +6 damage, but doubled when charging so 2d6 +8/12 (or numbers almost exactly what the medium-sized greatsword wielder would pull), plus whatever modifiers like the above you have, PLUS you'll be hitting with your animal companion.