In general, you fix causes, not symptoms. However, in this case, if the testes are not responding to HCG, then they will not work right if other systems are corrected and LH otherwise increases.
If DHEA was low enough to be rate limiting the testes, then there would be merit to what the doc suggests. However, you should take DHEA for other reasons as well. So no harm in trying, but the improvement would be an incremental improvement and based on where you are now, my expectation is that the result will not be sufficient.
Your T is low enough that the expected FSH/LH shutdown from the hCG has not occurred.
This outcome suggests a degree of primary hypogonadism. Short of a varicocele that could be surgically corrected, I don't know of any out of this. FSH is not deeply low.
We very rarely see Estrone labs and really do not what to do with such.
The only flaw that I can see with the above thinking is if your hCG is not dosed correctly. If you diluted to 1000iu/ml, you would be injecting "25" on an insulin needle. You are keeping it refrigerated?
What changes did you notice in mood, size and firmness of your testes and how they hang?