To answer your question,
No you can't use that box and just stick a few ports in it.
1. Ports require precise calculations, and a box built around those. There's 100x more to a ported box than you probably realize, no offense.
Advice
1.Sell 2 of your subs
2.Use money to build/get built new ported box
3.Never use 1/2" (Inch) MDF (Wood) when building a box, NEVER. Use 3/4" at a minimum. 1/2" MDF is worthless, they should save some glue and quit making it...imo.