Unfortunately, wind in Alameda is shutting down fast. It has been an unusual season getting 20 mph winds this month. Most of the people you have been seeing riding there this past week (including me) are foilers. What works for me there at the moment is a 8 or 10 meter kite and a F4 surf foil. I barely make it out from the beach to the ferry markers. The ferry markers is where the wind is, so if you make it out there, you get consistent winds. Inside, its a crap shoot. Once I get to the ferry markers I stay there and ride until I get tired and them come back to the beach.
Your best bet this time of the year is talk to the people at Sherman island who can ferry you upwind on their boat, from there you can do downwinders until you get back to the island. You can get assisted boat support maybe one or two sessions, and then once you get comfortable, you can just pay for the ride up the other islands and do unassisted downwinder.
Surfboards also work here in Alameda. I still use my 8 foot wavestorm foam board Costco special on light wind days with my 17 meter fuel. It is slow and clunky, but it works. You will also still be fine with your current 160 twin tip and big kite, but expect to go downwind half the time since you have not fully figured out how light wind sessions work in Alameda.
Buy a cheap shortboard on craigslist if you want to try the surfboard setup. Any 6 foot shortboard will do, at least you will not spend hundreds of dollars on boards and find out its not for you.
At this time of the year, Alameda is considered an advanced light wind spot, because if you are a beginner, chances are, you are either gonna go straight downwind due to light wind conditions, or will master self rescue because your kite will be down in the water most of the time.
Best time to go to Alameda is around 3 pm, ... wait for the thermal winds to kick in, ..., this means the heat in the valley will start breaking down and cooling, then we get a rush of cold winds from the ocean going into the bay around 4 pm, probably will get an hour or two rideable winds with a big kite and a twin tip, and then a complete shutdown.... its a waiting game until you figured out your personal light wind setup.
If you need additional help and guidance, I usually rig downwind of the (boardsports) shack by the bathrooms. Me and a bunch of locals there have switched to foiling this time of the year because wind in Alameda is unpredictable.
Rey