As for not gaining weight- I would compare this to atkins/paleo diet and lot of weight loss there is because of catecholamine- but lot of people dont tolerate them well and sides like increased blood pressure, sweating etc- actually lot of these affect are similar to those of thyroid hormones so lot of hypothyroid dont realise that they are hypothyroid.
Considering that you are on TRT- pregnenolone is no danger to you, do multiple doses a day (as its half-life is quite sure), it will defintely convert to progesterone hopefully it will overspill bi further- in any case short-term intevention is pretty safe and you can use higher amounts, no problem- start with 200-300 mgs and take it from there. After while if you like effects you can do blood test for PROGESTERONE, and adjust dosage according to that- best is close to upper limit, even if its bit above is not a problem.
Other option is to go natural.
Other thing is you can combine pregnenolone during morning/day and in the evening you can take phosphorylated serine- my mum does this and it works great, it kind-of mimic natural (circadian) rhytm
Some interesting info:
Adrenal Fatigue Chelation livingnetwork.co.za