Assuming this is AQA Science and the units are equally weighted at 25% each:
Translating each of your modules into percentages we get -->
B1 = 52%
C1 = 40%
P1 = 30%
ISA = 94%
This averages out to a 54% average in your GCSE Science.
Now by looking at last years AQA boundaries for Science GCSE core - you need 48%, 52%, 45%, and 74% for a B giving an average of 54.75%....
You got 54% and the B boundary was 54.75% last year - so either you get a B, or just miss it out by a hair and get a C according to my calculations..
However, this is assuming the grade boundaries from last year stay the exact same which is very unlikely, and if you feel the papers this year were harder than 2015 June papers, you probably got a B.