Can too little sand equal weaker concrete?
You will likely find this related question useful.

In general sand is added into concrete for two purposes - to save cement and to reduce shrinking of the concrete stone while it hardens. Shrinking causes cracks and cracks are really bad for most scenarios of using concrete.

You haven't altered the mix much so you likely won't have problems with shrinking and cracking.

Another point is that concrete needs water while hardening (after it has initially cured) and it surely needs more water if you added more cement.