Certainly a good summary of stretching progress, and much as we would expect.
The doctor: Nice to hear that he did not refer to circumcision; somewhat more intelligent than most (insofar as he clearly
comprehends the value of the foreskin, presumably from personal experience.

) however clearly confused about just what stretching entails. I wonder why - perhaps
he has been reading fetish material on the Internet where people
deliberately make misleading claims with an assortment of motivations!
Stretching the frænulum
is slower than stretching the opening, principally because you require a
much greater proportional growth; from 1cm to 4cm at the foreskin opening is a factor of four, while you might want to stretch perhaps 3mm of frænulum to 24 mm to allow for complete smoothing of the retracted foreskin, a factor of eight. Mind you, this is exponential - a four times expansion means doubling the dimension twice, while eight times means doubling
three times and so would take about half as long again to achieve.
Yes, if you stretch skin this rapidly, you
may well develop stretch marks - as do some (but not all) women during pregnancy (and in fact, puberty). Fortunately, this is unlikely to be subject to a
great deal of scrutiny.
Masturbation with the foreskin exposed
will be different, the otherwise protected glans will not be accustomed to such rough and dry treatment. Not sure you are saying you
have been having intercourse with a condom, or hypothesising. As always, I suggest that if the woman is
properly lubricated, there will be little or no friction and tendency to pull the foreskin back. The only difference between a tight and a loose frænulum really, is that where it is loose, the (same degree of) drag is distributed over a wider area of skin.
I do not advise
stopping stretching at any stage before completion (which is a month or two
after you achieve your desired dimension), but if you discern any problem you certainly may wish to reduce the tension used
a little.
Your description of stretching the frænulum sounds "spot-on". Clearly you
have assimilated our advice.