A few questions on stage one

Hi I have some quick questions to ask on stage one (although they can be applied to meditation as a whole).

Bit of background: Been meditating on and off for six months with some success but lately lost progress and skill due to inconsistency of practise. Bought TMI as a guide and to help me stay motivated every day.

• How do I stay focused on the "sensations of the breath", particularly at the nostrils? I ask this because when I try, the sensations are extremely subtle. So subtle that it often feels as futile and difficult as following an ant through a field.

• This leads to my mind automatically trying to visualise and almost make a movie of my breath for me to watch in my imagination. How do I stop visualising?

• How do I keep my attention on the sensations at a fixed point without following my breath as it travels?

• Lastly, this may sound silly but I find it really hard to allow myself to breathe naturally. Whenever I drop control of the breath and let it do its thing, I simply don't breathe. I end up being short of breath and feeling pretty uncomfortable. Where do I find the happy medium?

Thank you for reading, may you love with ease.