How frequently should I be lifting if I am no longer sore the next day?

I have been strength training for about 6 weeks now and I've gotten really good results. I do most things with 3 sets of 10, bench press (flat only) lat pulldowns, pec dec, squats, bicep curls, tricep extensions, and quad extensions and hamstring curls and situps. I've been doing full body 3 days per week up until recently I lifted once on Monday and once on Friday (No Wednesday session) and I noticed that I struggled more when I only lifted two times in one week. I've also noticed that I am no longer sore the next day after my workouts like I was in the beginning. I feel strong enough to lift more often than 3 times per week, and I think it's because I've been eating like a madman because lifting really makes me hungry, I usually get in at least 4,000 calories per day and 200g or more of protein. (I'm tall and thin, 5'11 140lbs) I'm wondering if I could lift maybe 4 or 5 times per week since I feel fresh everyday. Keep in mind though that I'm lifting heavy (for me), never easy stuff