If I understand your question correctly, you are asking about your grades and change of majors affecting your future...no?
I'd say make the switch if you feel you cannot be successful at engineering. I made the switch my freshman year and was one of the VERY few lucky enough to be picked up for advanced standing the following year (about to get through entire NROTC program sans scholarship).
You have 3 options as I see it.
1) Continue on in NROTC as is and go for "Advanced Standing" in the summer before your junior year. If you get picked up, you will collect a stipened and go on your 1/C cruise the next summer followed by a senior year and a commission. Basically you continue the program and pay your way through college. This was my route and I have no regrets.
2) Finish out the semester with a strong effort and talk to your unit about your chances at one of the PNS scholarships the CO gives out at his/her will.
3) Get out of program and apply for OCS after college (not advised).
Like I said, I made the switch from Mech E to Poli Sci after my freshman year and I finished out fine and with a pilot slot. I'd recommend you set yourself up for success (ie major in something you are going to enjoy/do well in). Your success within your classes, and the battalion leadership billets, will ultimately factor into your application for flight school with more weight than a technical major or not (though some weight is given over us non-tech guys/gals).
Don't forget, the formula for success as a Midshipman is multi-faceted. You don't have to be a rockstar in the classroom, per say, but rather a well-rounded Midshipman who is solid in all areas (PT, Leadership, Academics, etc).
-Jai5w4