I was looking at Google Earth at that area, and I see Weapons Test Ship 892 in a wharf nearby. On GE, the wharf where 075 went has three LNG carriers, one of which is red, possibly the same ship or ship of the class as the Knutsen OAS tanker we saw in the photo of Type 075 at the Shanghai Huarun Dadong shipyard. This part of the island might be HDZ's and not Jiangnan's. Sometimes the shipyards are set close, as Shanghai Shipyard's and Shanghai Huarun Dadong Dockyard's are set in Chongming---- both of these shipyards are traditionally in the Shanghai proper but closed their old shipyards, sold the land to real estate developers, and moved to Chongming. I think Jiangnan's shipyard is set next to HDZ's and another CSSC shipyard and they are sharing facilities, as all three are under the CSSC, now CSG banner. The three shipyards make up one super shipyard.
The proximity of the shipyards makes me think the 003 carrier might even be a joint project between HDZ and Jiangnan.
075 should be in the Hudong Zhonghua side of Changxing Island, which is right next to Jiangnan. The front of 075 and way further ahead should be the wharf where Test Ship 892 should be moored if she has not gotten another testing assignment lately.
At this point, this is much easier and safer for the ship to head into sea for trials than snaking in and out of the Yangtze and the Huangpu River for the old HDZ complex, which can risk collisions due to the high volume of ship traffic.
From the PDF.
The LNG carrier right behind her might be the LNG Megrez herself or a sister ship within the same build contract. This near 300 meter ship is a HDZ project for MOL (Mitsui OK Lines) and COSCO, to serve the Yamal route. The profound strategic implications of these ships for China's and Asia's energy security is another story. Identifying ships in the background also helps in further co-finding and confirming 075's location.
You should expect the ship to go trials with the warm waters in the South China Seas, as the ship is expected to be deployed there and you need to test all the cooling systems and so on. Didn't expect it to be this soon however.