Don't freak out- you'll be fine to go ahead and use your concealer on its own. As long as the colour match still looks ok with your skin tone, don't be afraid to go ahead and apply the concealer to problem areas. Just make sure you really blend the edges of the concealer around your blemishes so that there is a seamless blend between your skin and concealer. A bit of translucent powder all over would help to keep the concealer in place for longer, but you don't have to use powder.
Hope that helps!
And I've just seen your other post where you mentioned using q-tips. You can do that but products tend to stick to the q-tip and don't transfer onto the skin so easily. Personally I prefer to rub some concealer on to the back of my hand then apply with my finger from there, using my hand like a pallet. Whoever said don't apply straight to the skin from the concealer stick was right- as this does allow bacteria to harbour.