I'm a little confused which version you have going now, but IMO if you are wanting a big bold Robust type porter I would include some black malt plus chocolate (either regular or pale). For more of a brown porter style I like a lot of brown malt and some pale chocolate with very little if any black malt, usually I don't use any and instead include just a little debittered. So I guess it depends on what you want. You certainly don't have to stick to any defined style, but for the purposes of getting advice these descriptions might help you clarify what you are aiming for (these are from the 2008 guidelines):
Brown Porter
Flavor: Malt flavor includes a mild to moderate roastiness (frequently with a chocolate character) and often a significant caramel, nutty, and/or toffee character. May have other secondary flavors such as coffee, licorice, biscuits or toast in support. Should not have a significant black malt character (acrid, burnt, or harsh roasted flavors), although small amounts may contribute a bitter chocolate complexity. English hop flavor moderate to none. Medium-low to medium hop bitterness will vary the balance from slightly malty to slightly bitter. Usually fairly well attenuated, although somewhat sweet versions exist. Diacetyl should be moderately low to none. Moderate to low fruity esters.
Overall Impression: A fairly substantial English dark ale with restrained roasty characteristics.
Comments: Differs from a robust porter in that it usually has softer, sweeter and more caramelly flavors, lower gravities, and usually less alcohol. More substance and roast than a brown ale. Higher in gravity than a dark mild. Some versions are fermented with lager yeast. Balance tends toward malt more than hops. Usually has an “English” character.
Ingredients: English ingredients are most common. May contain several malts, including chocolate and/or other dark roasted malts and caramel-type malts. Historical versions would use a significant amount of brown malt. Usually does not contain large amounts of black patent malt or roasted barley. English hops are most common, but are usually subdued.
Vital Statistics: OG: 1.040 – 1.052
IBUs: 18 – 35 FG: 1.008 – 1.014
SRM: 20 – 30 ABV: 4 – 5.4%
Robust Porter
Flavor: Moderately strong malt flavor usually features a lightly burnt, black malt character (and sometimes chocolate and/or coffee flavors) with a bit of roasty dryness in the finish. Overall flavor may finish from dry to medium-sweet, depending on grist composition, hop bittering level, and attenuation. May have a sharp character from dark roasted grains, although should not be overly acrid, burnt or harsh. Medium to high bitterness, which can be accentuated by the roasted malt. Hop flavor can vary from low to moderately high (US or UK varieties, typically), and balances the roasted malt flavors.
Overall Impression: A substantial, malty dark ale with a complex and flavorful roasty character.
Comments: Although a rather broad style open to brewer interpretation, it may be distinguished from Stout as lacking a strong roasted barley character. It differs from a brown porter in that a black patent or roasted grain character is usually present, and it can be stronger in alcohol. Roast intensity and malt flavors can also vary significantly. May or may not have a strong hop character, and may or may not have significant fermentation by-products; thus may seem to have an “American” or “English” character.
History: Stronger, hoppier and/or roastier version of porter designed as either a historical throwback or an American interpretation of the style. Traditional versions will have a more subtle hop character (often English), while modern versions may be considerably more aggressive. Both types are equally valid.
Ingredients: May contain several malts, prominently dark roasted malts and grains, which often include black patent malt (chocolate malt and/or roasted barley may also be used in some versions). Hops are used for bittering, flavor and/or aroma, and are frequently UK or US varieties.
Vital Statistics: OG: 1.048 – 1.065
IBUs: 25 – 50 FG: 1.012 – 1.016
SRM: 22 – 35 ABV: 4.8 – 6.5%
