Sulphur aroma is usually an issue with lagers and not so much with ales. However, it doesn't mean that they can't happen. I'm going to be quoting a lot of this from the book "Yeast" by Chris White, with Jamil Zainasheff.
The lower temperatures of lager fermentations produces large quantities of sulphur compounds, but strong fermentation activity drives them from solution along with the CO2. Lower temperatures of lager fermentation means less vigorous fermentation and more likelihood of sulpher compounds. However, you're having this issue with IPA's and that is unusual, but not impossible.
As quoted in the book 'Yeast", "The sulfur coumpounds typically found in beer are dimethyl sulfide (DMS), sulfur dioxide, hydrogen sulfide, and mercaptans. Some of these sulfur compounds come from malt, while others come from yeast or a combination of both. For example, dimethyl suphoxide (DMSO) is present in wort at varying levels, depending on the source malt. The level of this oxidized DMS coumpound is not affected by the boil like DMS or its precursor S-methyl- methionine (SMM). Unfortunately, yeast has the ability to redue DMSO back to DMS during fermentation, increaasing the level of those canned corn or cooked cabbage types of aromas and flavors in the beer." "Yeast produce sulfur dioxide, which not only flavors the beer but gives it antioxidant properties. People often describe the aroma of sulfur dioxide as similar to a burnt match. Sulphur dioxide easily reduces to another sulfur compound, hydrogen sulfide, which is the coumpound with a rotten egg smell. Fortunately, the CO2 released from fermentation carries most of the hydrogen sulfide out of the beer. The key to reducing these sulfur counpounds in beer is to have an active, healthy fermentation."
So, after quoting all of that and wading through it, we see that some sulfur compounds will be in the beer, but healthy fermentation will carry most of them back out. From reading through your procedures, I see you saying "No oxygenation to speak of besides dunking the wort chiller during chilling." If you're dunking the wort chiller up and down when the wort is hot, or even warm, you'll get hotside aeration. I put my chiller into my kettle at 20 minutes left in the boil to sterilize it. Then I run cold water through it and let it do it's job. No dunking or splashing. Once my wort is down around 100F, then I might stir to help it chill faster.
If you're dunking up and down and splashing, it could lead to DMSO, since there is probably DMS in your wort and it will bound with the oxygen created at those higher temperatures. As a disclaimer, I'm not a chemist, so this is just a guess about DMSO and DMS. Also, do you have a lid on during the boil? If you do, you'll keep DMS in your wort, that would normally have been driven off during the boil. In addition, a vigorous boil is what will drive DMS out of your wort. If you aren't boiling vigorously enough, you'll have more DMS in your wort.
As for fermentation, I suggest you give your yeast time to do their job. I never do anything with fermentation based on time. I do things based on yeast activity and give them enough time to do their job. Become a yeast whisperer. One week may seem like enough time, but, if you rack to a secondary before they're done cleaning up after themselves, you could cause them to get sluggish and not finish at all. This could lead to some sulfur compounds not being carried out with the CO2.
Based on all of this, my suggestions are:
If you have a lid on your boil pot during the boil, take it off.
Make sure you have a good rolling boil. I keep my boil vigorous enough that it's rolling, but not boiling over.
Don't dunk or splash your chiller.
Be patient with your fermentation and give it more time.
I hope this is helpful.
