How can I focus on breath at the tip of my nose?

“Ānanda, there is that concentration to the bhikkhu, in which, the eye and forms do not attend reciprocally, the ear and sounds do not attend reciprocally, the nose and smells do not attend reciprocally, the tongue and tastes do not attend reciprocally, the body and touches do not attend reciprocally. The mind does not attend to earth, water, fire or air, as earth, water, fire and air. The mind does not attend to the sphere of space as the sphere of space, the sphere of consciousness, as the sphere of consciousness The sphere of nothingness as the sphere of nothingness and the sphere of neither perception nor non-perception, as the sphere of neither perception nor non-perception. The mind does not attend to this world as this world or attend to the other world, as the other world. The mind does not attend to whatever seen, heard, experienced, cognized and searched by the mind, as the seen, heard, experienced, cognized and searched by the mind. Yet the mind is attentive.

Above is from Anguttara Nikaya -> Ekadasakanipatha -> Nissayavagga -> Manasikara sutta where it clearly describe that concentration on air, or senses (nose, skin etc) is something not advised to do.

But this collides most of the popular teachings and teachers today. Why is that? I'll explain why with another quote from the cannon.

Samyutta Nikaya -> Nidanawagga -> Nidanasutta -> Mahawagga -> Duthiya Assutava Sutta

1. I heard thus. At one time the Blessed One was living in the monastery offered by Anāthapiṇḍika in Jeta’s grove in Sāvatthi.

2. “Monks, it may happen that the not learned ordinary man would turn away, lose interest and be released from this body of the four elements.

3. “What is the reason? Monks, in this body of four elements, he sees the heaping up and the dwindling, the appropriating and discarding natures. Therefore the ordinary man turns away, loses interest and is released from this body of the four elements.

4. “Monks, there is no cause for the ordinary man to turn away, to lose interest and to be release from the mind, or the mentality or consciousness

5. “What is the reason? Monks, for a long time the ordinary man had clung to it, made it his own and touched it as ‘this is me, I am this and this is my self.’

“Therefore, for the ordinary man it is not sufficient to turn away, lose interest and be released from the mind, mentality or consciousness.

6. “It is suitable that the ordinary man should conclude, this body of the four elements is my self rather than the mind.

As you see above most of the popular teachings and teachers are not nobles, they just teach what they understand as the truth, which is 100% align with the latter quote from the cannon. The reason is simple as explained above there are cause. Which means they are not in the right view, or they are not first entrants.

Now you may think your way of meditation works as well, and what's the wrong about it. Yes of course it works, but that's not the noble meditation which Buddha advised (evidences are in the first quote). Those kind of meditations were there from very old days. Even prince Siddharath (buddha's earlier name) were capable of doing that after attending to his first three teachers (Alarakalama, Uddakarama...). But with those prince Siddhartha couldn't find the Nirvana, the ultimate happiness. That's why he left those teachers and find his own way.

So it's natural that why the wrong ways are very popular and known by many people while the real truth is hidden ( in this forum it gets down voted, but I'm doing my duty by sharing what I know and what I've understood)

So to wrap up my answer before someone says this is not an answer but an explanation, The meditation you are doing is not what the Buddha has advised to do, so without directly answering the question, I'm trying to answer with an explanation why the question is wrong.

With Metta..!

PariMukkhaṃ Satiṃ upaṭṭhapetvā = the practitioner focuses the mindfulness on only Breaths.

So satova assasati satova passasati = he is focusing the mindfulness like that and breathing out/in.

Breaths are not nose tip, touching, or feeling. Breaths are long or short wind flowing at nose tip.

Sometime breaths appear at right nostril tip, sometime left, sometime middle, some time top lip.

But you are focus on clearing appearing breaths at somewhere of those, so wherever of them is OK.

The other touching points such as in side the nose or lung is over width for clear focusing on breath and easily to get Restlessness (uddhacca), so appearing breaths on somewhere at the nose tip is the best choice for the meditation.