1st, letro does not need a nolva taper. It is not an anabolic steroid and does not shut down your natural production of test.
2nd, puffy nipples could be a result of bodyfat levels. If youre fat, your pecs and nips may be puffy.
3rd, if it is estrogen related, you would want to start with arimidex and a very low dose instead of letro, because imho it is easier to dose predictively.