You cannot simply go into an exam with such a limited and basic range of literary techniques, it just won't be a stong evaluative/critical response. You need to analyse each of your texts in depth, picking up on a wide range of literary/poetic/filmic devices which shape meaning, then go on to explain why the composer used these techniques and how they position us as an audience.
Look on the internet for literary/poetic/filmic techniques, go through your texts again and ANALYSE like you mean it. Ask yourself:
1. What techniques are used here? (if you look hard enough, there will be at least one per sentence/line of poetry/scene of film)
2. Why is the composer using these techniques?
3. How do these techniques shape meaning? What effect do they have? How do they affect our response to the text?
4. LINK THIS BACK TO THE QUESTION.
For a belonging essay, your response should be driven by ideas and concepts rather than just chunks of textual analysis. So look at the question, develop some ideas and thesis statements which you can argue, and work out which bits of your prescribed and related texts will best fit the views and argument you are presenting. Open with a perceptive, concise and interesting overview of your ideas in regards to the question, then go from there, remembering to continue arguing the same point the whole way through your essay. This means you will have a structured, logical and coherent response, which is necessary for a Band 5 or 6.
3 pages is definitely NOT ENOUGH. With medium sized handwriting, you should be aiming for somewhere between 5-8 pages of a standard writing booklet in a 40 minute timeframe. However, remember it is quality, not always quantity which will get you marks - don't faff on about nothing just to fill up pages. But if you analyse your texts thoroughly and properly, draw out some insights about belonging and it is clear that you know your texts well and have clear and supported ideas, you should be fine.
No your teacher was probably not being hard on you, you just need to spend some more time on your response and work on making it better (including more depth). Try and find some Band 6 sample responses and compare these to yours. Look at what other kids are doing right and adopt (BUT NOT PLAGIARISE) some of their strategies.
Hope this helps
