In the specific situation where one is feeling the inclination to kneel, in the GIRM it does state that it is best to in a sense “Follow the Crowd” or be obedient, If one is to do a different, personal practice then they must first present it to the Priest who is presiding over the Mass. (I.E. If the norm is to stand during communion in your parish, then you should ask the Priest if he would allow you to kneel)
In the case of kneeling during the Consecration, it does State in GIRM 43 quote “In the Dioceses of the United States of America, they should kneel beginning after the singing or recitation of the Sanctus (Holy, Holy, Holy) until after the Amen of the Eucharistic Prayer, except when prevented on occasion by ill health, or for reasons of lack of space, of the large number of people present, or for another reasonable cause. However, those who do not kneel ought to make a profound bow when the Priest genuflects after the Consecration. The faithful kneel after the Agnus Dei (Lamb of God) unless the Diocesan Bishop determines otherwise.”
Note, that the changing of the Posture requires the Diocesan Bishop to change it, therefore, not giving that Authority to the priest. In the case of a priest doing so, it is suggested further in GIRM 43… “For the sake of uniformity in gestures and bodily postures during one and the same celebration, the faithful should follow the instructions which the Deacon, a lay minister, or the Priest gives, according to what is laid down in the Missal” Therefore, be obedient, but bring up the missal in which case it does give explicit instruction to kneel.
Overall, be patient with your priest, or if you are visiting a Parish, be patient as well, do not draw attention to yourself by causing a commotion; It would be better to allow the posture to continue and focus to remain on the Eucharist, than do that.