So if you like spears and heavy defense you're probably going to want to use a great shield, which means you'll want high strength. 50 is the highest you should go, but also isn't totally necessary. It would allow you to use Havel's Great Shield, which is arguably the best shield in the game, but is very heavy to equip. The Stone Great Shield, and Great Shield of Artorias are also good choices. Havel's can be found in a secret room in the Cathedral in Anor Londo, the Stone Great Shield is a rare drop from the stone guardians in Darkroot Forest, and the Great Shield of Artorias can be made from the Soul of the Great Grey Wolf Sif. As far as spears go, most of the them scale either D,C or C,C with strength and dexterity, meaning you'll want to start increasing your dexterity also in order to be as effective as you can be with them. Some of the better spears are the Pike, which is one of the heavier spears, as sold by Andre of Astora, the Blacksmith near the Undead Parish, The Partizan, which is found in the Darkroot Forest, the Silver Knight Spear, which is dropped by the spear wielding Silver Knights of Anor Londo, the Dragon Slayer Spear, which is made from the Soul of Ornstein, which is attained by killing Smough first when you fight Ornstein and Smough, and the Moonlight Butterfly Horn, which is made from the soul of the Moonlight Butterfly. The last two. the Dragon Slayer Spear, and the Moonlight Butterfly Horn, would both require you to start upgrading another stat in order to be used the most effectively. The DSS requires faith, and the MLBH requires intelligence, however I kind of recommend you do one or the other as a spear user anyway. Either one will help provide you with spells that will bolster the amounts of damage you can do, and either one can help you to use buffs, and make your spears even more powerful
As far as armor, if you like heavier stuff, consider picking up the Elite Knight set in the Darkroot Forest, for now. It's just a medium set, but it will be a nice placeholder until you get to Sen's Fortress, where you'll gain access to heavier things, and then Anor Londo where you'll gain access to even heavier things than that. The Steel set in Sen's, the Black Iron set, and Havel's set, both in Anor Londo, are all good choices.
You also should continue to level your Vitality and Endurance, as both are helpful stats on a more basic level. Your Vitality will literally help keep you alive, as it increases your life, and your Endurance will help keep you mobile and allow you to equip heavier gear and stay fast. Vitality basically caps at 50, and Endurance caps at 40. So I recommend that, if you want to continue leveling, that's where you go with them.
With your Strength stat as high as it is already I also recommend that you upgrade your spears using the standard upgrade path. Meaning that you should not make them lightning, fire, or chaos, as that will negate the high strength stat you have, and the dexterity stat I recommend you start leveling. If you go with the standard upgrade path, I also recommend you attain a buff. Which means you'll have to level either your faith or your intelligence, but don't level both. If you go with intelligence, then you'll want to start buying spells from Griggs and Logan, which will eventually lead to you being able to purchase Magic Weapon, Great Magic Weapon, and Crystal Magic Weapon, for your spears. If you go with faith, you'll want to start buying spells from Petrus and Rhea, and eventually either kill Gwyndolin, or become a Darkmoon Blade, which will allow you to either attain Sunlight Blade, or Darkmoon Blade.