I took aggression as a PSYA3 module and got an A* in Psychology, so hopefully my advice will be useful, although your teacher is obviously the best source.
Firstly, you need more content. Ideally quote a few more studies or academics, but at the moment you simply lack the content to achieve the highest marks, in both AO1 and AO2 (especially the latter).
Your AO2 should start with the research that supports, and then the research that contradicts, the theory. The bulk of AO2 is evaluating the evidence for and against the theory you described for AO1. At the moment, the study you cited was only described, so would count at AO1. I suggest expanding your description of the theory and using that study, and others, as AO2 by explicitly stating how they relate to the validity of the theory.
Be careful with saying that evolutionary theories don't take account of biology - they almost certainly do. Evolutionary theories explain the overall trends and ultimate causes and explanations for behaviour, whereas biological theories explain the immediate causes. You also in the paragraph about biology stray too far from the question. The question is about evolutionary theories, don't get bound up describing biological theories in any great detail.
Expand upon your determinism point - what evidence is there to suggest that people can mediate their responses to infidelity or aggressive feelings?
Lastly, spice up your final point. Evolutionary theories are fairly unscientific; they lack falsifiability and proper empiricism - two of Popper's criteria for effective, valid science. You can't falsify evolutionary theories for the same reason you can't find proper empirical evidence for them - we can't observe evolution of the brain or behaviour.
I'm not experienced enough to give you a grade, but I doubt this would be an A/A*. Take on board some of my suggestions and you can definitely get your essays up to the highest grades. PSYA3 is a tough module - I'd say it was the hardest of any of my A-Levels, so don't feel bad if you're finding it tough, because it is!