Well, it seems to me you have summed up your little method fairly well. I
would rather like to know a little more about the bleeding matter - where the bleeding occurred and when; I
presume you may be saying it was noticed as a consequence when you woke up in the morning.
A few observations on this, which may differ somewhat from what Jim says: Clearly you realise that you have erections during the night; as a teenager these are most likely quite strong and persistent, possibly totalling a couple of hours erect, which certainly sounds like a potentially attractive way of stretching without "effort".
The risk of "paraphimosis" in your circumstance is relatively trivial as clearly you would wake (though people under the influence of drugs, prescribed or otherwise and of course including alcohol, might not) if there was any substantial discomfort as a result of this practice during the night, and would promptly pull your foreskin forward again, by grasping the skin on each side behind the narrow part and simply pulling it forward over the glans with whatever persistence and force necessary.
Now clearly you
have stretched your foreskin open to some degree, as it now slips itself back over your glans when you have no erection. If you
want to hold it back, use sticky tape - preferably the "surgical" tape with the appearance of paper - three small pieces spaced out around the foreskin rather than a continuous ring, to allow comfortable movement and expansion.
This method will work
to a degree but will not be sufficient as you need to stretch significantly
beyond the dimension you need and you will need a
much more effective method to properly stretch the frænulum. But yes, it will improve things somewhat.
I am sure that you can find a perfectly adequate description of stretching methods by reading back through the forum here. Don't just read a
few threads here, read a few
dozen - the whole contents of at least three or four index pages.
What you
may find useful if you want a really "minimal effort" approach, is the use of "
flesh tunnels" - have a read of those links too.
Finally, frænulum tying. Well, that is one way of dealing with a short frænulum. I'm not totally against it, because I don't strictly believe
all the "hype" about how sensitive the frænulum is. Clearly that area
is sensitive and important, but it is also true that tearing the frænulum - as often happens - causes little (if any?) loss of function (after it heals). It would be irresponsible of us however to encourage people to attempt
any form of surgery on themselves without a degree of skill which is hardly practical to convey over the Internet - let alone assuming we could somehow evaluate their potential competence.
If you already had that skill, then perhaps you could do this; otherwise it is better to advise that if you really,
really wished to have this done, then a General Practitioner or "Family Physician" -
not a "specialist" or "urologist" - could do it for you as a "rooms" procedure - no hospital or "operating theatre" involved.
In the meantime, I do suggest you "knuckle down" to stretching and if you
are that impatient (hey, you did specify that you are a "teenager"

) then research the "
flesh tunnels".