Ah, knives - figured as much. You're definitely not, by going DEX, cornering yourself into a knives-only playthrough.
Like I said, when I did my first and only complete playthrough, the game was new and ADP was in the unceasing process of being theory crafted, so I can't help you much there - the info on its efficacy just didn't exist and I allocated most of my early stats to vitality and endurance. If you're still looking to do some sort of DEX or STR / magic of some sort build, the Fire Longsword from a tunnel in that first forest area serves as a viable substitute for the Heide Knight Sword I was talking about. I don't like it as much, but it's got that same modest scaling in a lot of stats + elemental damage that endeared me to the HKS. They're both ultra quick and have nice, fluid movesets that'll serve you well until you get a weapon that better serves your build as you envision it.
I'd advise against spear usage on the grounds that it's (imo) not a lot of fun. Poking and guarding makes you hard to kill, to be sure, but I never found the damage at all comparable to a more offensive weapon, and you're robbing yourself of a better experience. There are plenty of swords, scythes, halberds, katanas, etc that scale well with dex that you'll have a lot more fun using.
If you do wanna go defensive, a str-based sword and shield build is a lot more fun. That's what I did for the first 75% of my first playthrough before I embraced rolling (thanks Bloodborne).
As an aside, if you dig this series as much as I hope you do, make sure you interrupt whatever you're playing and start Dark Souls III (when it comes out) on day 1. Just winging it and going as far as you can and comparing your progress with people on various forums is a lot of fun, because in-game suggestions are so vague and many mechanics are shrouded by ignorance. I remember somebody here talking about the Lost Sinner (from Sinner's Rise zone) wrecking their shit all night on like the second day of release, but that was one of the last zones I went to before progression converged on endgame zones.
edit: sorry if this meandered. drunk as fuck.