recipe improvement - nut brown ale

Please help me improve on this 3 gallon nut brown recipe:

5 lbs Maris Otter
0.5 lbs brown malt
0.5 lbs C-80L
0.5 lbs briess special roast
0.33 victory malt
0.15 lbs chocolate malt
1 oz Willamette (60 min)

S-04 yeast
mashed at 153 for 1 hr
fermented mid 60s
OG: 1.051
FG: 1.018

This was my second all grain batch, and it came out alright tasting, but I'd like it to finish with a lower fg but still keep the nutty/toastiness. Also thinking of adding more late hops.
Thanks!

can anyone help me out?

Some ideas in terns of the FG question: You could mash a little lower, check your mash ph, make a yeast starter, oxygenate the wort before pitching, and use a higher attenuating yeast like WLP007.

for browns I use nottingham, seems to work better with dark beers.

gbarron has steered you right. Mash a bit lower should be the first change to lower your FG. Also make sure you have a large enough volume of yeast by using a starter. The only other thing I could think of is to supplement your fermentables with some form of sugar--something like Candi Sugar or even simply dextrose--to dry it out. Of course the Reinheitsbegot crowd just got their lederhosen in a bunch when I said that.

thanks for all the replies. I used S-04 yeast for this batch and every time I use that yeast I seem to get a high FG. I just brewed a Vienna/NB Smash with US-05 and the FG came down to 1.012, so I think I'm generally ok with my process. I was more interested in if the ratio of ingredients is "correct" (right percentage of base malt, specialty grains, etc). Thanks

Northern English brown is not a style I brew often but I just happened to recently brew a variation on Jamil's version from Brewing Classic Styles. The grist is roughly:

88.5% English pale ale malt
4.5% Victory
2% Crystal 20L
2% Crystal 60L
2% Chocolate

That may not quite add up to 100% but you get my drift. It is still in the fermenter. But you might compare that to your own grain bill.

thanks, those percentages help out a bit. i think i should use more base malt and less of everything else