Personnaly, I'm not that good in math either but I would mostly use the Pythagore theorem .

Take Wolf for example. You already draw the line arriving at the Sun's equator. I'll refer to this as the dot.

First you need to find the distance between the dot and the Sun. You can do that by tracing a circle, like the others, one that intersect the dot. To find the distance, look where that circle crosses the x axis, from right to left. Since your actual circle is 5 ly , you can find the distance by using the cross multiplication, after mesuring the distance berween sun and dot.

After that, you find the distance between the dot and wolf. This is easy. Mesure the distance cross multiply it with your scale.

Now you have 2 of the 3 sides of the triangle, use pythagore to find the actual distance between sun and wolf.

That's the sinpliest method I can think of.