Nice job. One bit of free advice and it's alright if you don't take it: If you want your drawings to look realistic, try not to draw the lines around the subject(s)/object(s).
If you take a close look at any object or person, you will not see outlines bordering unless of course the object your looking at is another line drawing. Try looking at your face in the mirror for example. Notice that there is only a change in color or shade but no actual lines? This is how you put contrast into your sketches or pencil drawings.
Try practicing it and have fun with it. You definitely have talent.