First off for two months in you are doing EXCELLENT. Not pathetic at ALL. I know people who took YEARS to be able to run that far. You dont want to change too much too fast. Mixing it up can help prevent boredom though

The following is all suggestions on how you MIGHT want to proceed..they are just examples of possible ways, but certainly you are doing awesome if you just continue on as you have been for awhile.

If you would like to work a bit on speed (this is COMPLETELY not necessary at this point) then ONE day a week warm up at your current pace for 10 minutes. Then increase your pace SLIGHTLY...maybe to 4.3 for 1-2 minutes and return to your normal pace for 2-3 minutes. Do 2-4 intervals like that, then cool down at your normal pace. This day can be shorter than the other 4 days. See how it feels. On your ONE speed day a week, play with pace. Find a pace that you can do the 2 minutes without struggling too much and that you can feel recovered from after your return to normal pace.

On your other 4 days maintain your current pace and keep adding distance until you get to whatever your comfortable goal/workout time. (i.e. 3 miles @ 4 mph is 45 minutes--that is a really good length for a cardio workout)

When you are comfortable running THAT distance on your normal days try mixing things up a bit. Perhaps:

Day 1 - keep going at 3 miles @ 4 mph (baseline day)

Day 2 - do 3 miles @ 4.1 mph (push the speed day)

Day 3 - do the speedwork day

Day 4 - do 3 miles @ 4 mph (baseline day)

Day 5 - do 3.2 miles @ 4 mph (push the distance day)

Eventually you might get to a point where you say HEY...I can move my baseline up a notch and proceed. But on the day I try to run farther, I stay slow. On the day I try to run FASTER I run shorter. etc.

Hope that helps some... dont get too overwhelmed. Pick ONE thing to do and do that for a few weeks and see how it feels before you change something else.