On Southwest, shouldn't the 30 credits have been turned into one domestic-US (excluding Hawaii) award and 14 credits automatically? Don't forget the expiration date of the award. Two more credits (one round trip on Southwest, or four car rentals or hotel stays, should do it) will get you a second award. Then you may want to decide whether you want to continue to use Southwest, or concentrate flying on another airline. Southwest is good for collecting domestic-US award flights from short flights and short car rentals, but does not offer status or upgrades or international flights, and its one point per flight system is not very good for long flights.

UA and US are in a single alliance (Star Alliance), so concentrating mileage from both on one program makes sense.

DL has NW and CO in its alliance (Sky Team). AA is in the OneWorld alliance. The only way to collect future mileage from these four into one program is to do it on an airline that has mileage partnerships with all of them, such as AS (but you'd have to give up collecting on the existing programs).