Running shoe for narrow feet with deep heel to fit othotics?

SRH7

Feeling utterly, utterly fed-up. Started C25K last week, loved it and really feel like I could be a runner! I've been running in some old Nike cross trainers I've had for years so today plucked up the courage (and got my credit card ready) to go to a running shop.

I always have trouble buying shoes as I have very narrow feet (UK women's size 6.5) and also have to wear custom orthotics with a heel lift from my podiatrist. As I have knee problems too, my podiatrist said it was vital I got really well cushioned shoes.

The chap at the store was helpful (it was one of the big chains of running stores) but every single shoe he brought out did not fit. First up was Asics Nimbus - fitted great at the back but there was nearly an inch of spare room at the sides on the front of the shoe. We then proceeded to work our way through Adidas, Mizuno, New Balance etc etc. I tried on 12 different pairs.

Every single pair was massive around my toes with fabric flapping around every time I jogged up and down the store.

Then, finally, he pulled out a pair New Balance 890v2. Hurrah! They fitted me like a glove around the front. So much so that neither he nor I really paid attention to the heel (hey, I'm a newbie!). I got home, got straight into my running gear and went out for a run in the freezing, driving rain.

Oh dear...

Throughout the run my foot felt like it was going to pop out the back of the shoe. My feet and ankles started to burn and I stopped and tightened the laces as best I could. I've got home and have red marks at the front of my ankle from the laces and my feet and knees are killing me (they are very low and I'm not sure they have the amount of cushioning I need).

I feel so stupid and annoyed. I'm going to take them back to the shop. It's going to be embarassing (don't like complaining) but they really are no good for me.

Sorry this is a bit long! But... a few questions that seasoned runners might be able to help me with:

1. I'm a size 6.5. The shoes he brought out were all 7.5 and 8 - is this right? Could this cause extra bagging if the shoes are too big?

2. Any recommendations on shoes? Which brands are narrower and/or have a deeper heel? I'd like to go armed with some idea of shoes that I could try when I go back.

3. Although neutral shoes are best for cushioning and my othotics already correct my overpronation, might a slight stability shoe give me more ankle support?

I've emailed New Balance this query too as they seem to be the only brand I've seen that does a specific narrow fit.