Hi @eloise89,
Thank you for your question.
What you've done already is a great start, but yes you will need to use more filler.
Somewhat counterintuitively, applying more plaster across a much wider area will blend in much better than if you try to end the filler right up against the patch.
I would suggest you apply a second coat of filler, and you apply it on top of the patch and about 100mm around all sides. Going wider with your patch will allow you to apply a slightly thicker coat over the patch and feather it out as you go wider, which will hide the slight variation in height.
Once you've applied the filler, give it another sand, then prime and paint.
Let me know how you go and if you require further assistance, don't hesitate to reach out.
Jacob
