I was in your same shoes, Qualitee about 5 yrs ago. MBL relaxed hair, wanted to transition, tried a few times, but would break down and relax. I didn't want to BC. Finally, in late 07, I chopped all my MBL hair to a 3-4 inch long relaxed fauxhawk, then I let it all grow out for 13 mos...I chopped again in mid 2008, which was a BC to go natural. I had a TWA, but didn't care cuz I was rocking braids, headwraps, etc. It grew back out to APL stretched in about 5 mos, then I texlaxed for convenience in Nov. 08, and maintained the texlaxer every 3-4 mos until July 09 (had a newborn at home, which was reason for 1st texlax app on virgin (natural) hair).
Now I'm transitioning again, but this time without a BC. I have BSL hair unstretched, MBL stretched. I don't mind the shrinkage, I've gotten used to it. I want to see how long my hair will grow--PERIOD, whether fully natural or not. If I can reach my goals with half natural, and half processed hair, then so be it. I've adopted the personal mantra that I will never drastically cut my hair again. I just prefer long hair, for looks, spiritual, and convenience reasons. My hair has a soft curl pattern, so it stretches easily. Shrinkage is just a natural part of having any hair texture aside from 1 or 2 types.
In order to be fully natural one day, I'm just trimming a small amount at a time...kind of going the route of YT's TheMakeupVirgin, who grew her relaxer out over like 8 yrs, and still has a few relaxed ends (she's now WL or longer). Love her hair, bTW