Did you need to prime the doors? If they were unfinished, they would have needed a coat of oil base primer…

What kind of finish coat paint did you use? Use ONLY high grade products like Sherwin Williams Classic-99 (for interiors) or A-100 (for exteriors) … use a semi gloss finish in either case…

Using a 3/8 inch to 1/2 inch in roller cover should give good results… the trick is to go over the door after it has set up for about 15 min, with a "dryer roller" (it still has paint on it but it has been rolled out enough, so that it will tighten up the stipple on the door to give a finer finish)…

Right now you will need to block sand the rough surface smooth using coarse grade paper and a block sander… then "start over"… following the info above, ie with primer…