Sometimes the little white dots you see on milkweed are dried specks of sap that come from damage to the leaf. I see that quite often, especially in conjunction with aphids and earwig infestations. Can't tell you how many of those specks I tried to raise years ago as a newbie . As a general rule , if you brush a white speck of sap lightly with a small brush or blade of grass it will fall off right . Eggs are adhered much better and won't budge if you gently brush up against them.
There is also a type of yellow aphid that feeds on milkweed, but usually you will see these in colonies, though I have seen single ones on the underside of leaves when looking for eggs. They are soft bodied and will move and/or brush off easily if disturbed.
As a general rule, sap specks are the same color as the sap inside the stem of the milkweed, whereas Monarch eggs are a creamy ivory or pale yellow, have a definite cone shape to them and come to a point. If you use a magnifying glass when searching for eggs you can see much better and will even be able to see the striped texture on the sides. Sap specks may be as large as egg but are round and smooth.
Somewhere on here are some great slide shows posted with some egg pictures. I am new to this forum, so not sure what thread I saw them in, but perhaps one of the other members or a mod could point you in the right direction.