Because my fingers are slender, and my finger tips are quite small, I'm having an insanely hard time holding down the E and B strings at the same time. I can do it as long as my other fingers can float in the air. As soon as I try to place my middle finger, it all falls apart for the index finger.

That's the tough part isn't it? We've all been there. While there are always other ways to play things, I say keep at it. It will come. Don't try to hold the strings down with your fingertip, but use the pad of your finger to hold them down. Keep at it. 4 days?! It took me weeks to get an F to become second nature.