It's a charming painting B. Love the colours and don't mind the texture on these small canvases.
For os2013 (and you if you need it!) -
A circle has two axes, vertical and horizontal and they MUST remain ar right angles to each other ... so, if you tilt them to get the angle of the elliptical object, make sure they still remain at 90* to each other.
Visually measure the height of the object and mark your vertical axis at desired angle, then visually measure the width (use eye and pencil at arm's length if necessary) and place that at right angles to the vertical.
Carefully draw your ellipse from point to point of the axes - you'll need to practise this!