Starting from the end of the right needle you should have the 12sts cuff sts (actually 11sts but if it's 12 that's ok) on the right needle and then the 11sts from knitting the 14rows of the instep. On the left needle is the 11-12st from the other side of the ankle cuff.
Move the 11 instep sts to the left needle by just slipping them back to the left needle (not by knitting or purling them back).
Now start with a new end of yarn and pick up 7sts along the side of the instep. This is where you correctly mention a gap. Now you're going to fill in that gap by creating a new st ~every other row. Take a look at the video
under Tips for picking up sts to see how to do this.
After you've picked up the 7sts, knit the 11 live instep sts from the left needle to the right, pick up 7sts down the side of the instep and knit across the final 12 (or 11)sts of the cuff that have been waiting on the left needle.
Now you'll have all the sts on the right needle, all connected and no gaps at the instep.