Okay - well, if you can do HIIT for 30 minutes, EITHER you're not really doing HIIT, OR you're in absolutely AMAZING shape. I can manage true HIIT for about 8 minutes, and then I feel like I'm gonna DIE!
If you're happy with your progress, leave your schedule alone.
Personally, I'd be dreading getting to the gym and feeling overtrained if I did this much, but I'm 11 years older than you, and that might have something to do with it.
Personally, I'd increase the lifting work and drop back the cardio a bit. If you're working hard, there's no need to hit a body part more than once a week, but 30 minutes isn't very long, so I'm not sure what you're doing weight-wise.
I lift hard for about an hour 4 days a week, and right now I'm cutting, so I'm doing a bit of post-lifting cardio on all but leg day, plus extra on whatever non-lifting days I can manage, either in the form of HIIT or longer-duration moderate intensity cardio (brisk walking). My bike rides are longer, but they're mostly for entertainment - the exercise is a side-effect.
You can, and probably should, vary your programme a bit from time to time - up the lifting for a bit, drop it back for a bit, change up the combinations, there's lots of ways to do this.
And at 5'6" and 127 pounds, you're most certainly very slim, so I'm sure you aren't all that worried about your figure at this point.
Cheers!
- Built