For fleets and battle groups that have the word "CONFIRMED" next to them, this means I have found a specific reference to that particular fleet and its base system in the FS1 and FS2 games from either a command briefing, the technical database, or a debriefing comment. The rest of the fleets and battle groups I had to extrapolate and do some guess work. I deduced that there were 26 GTVA battle groups from looking at the technical database entry for the GTM Hornet missile, which said that 2.6 million+ Hornet missiles had been stockpiled after the Great War and they were evenly distributed to all of the GTVA battle groups/fleets with each battle group and fleet getting at least 100,000 Hornets each. So 2.6 million divided by 100,000 = 26 fleets/battle groups. I knew that there were at least 12 Terran fleets because of the reference to the 12th Fleet at Ross 128 that I found in a debriefing and the tech database mentions the 13th Battle Group at Deneb in the description for the GVD Hatshepsut. So I reasoned that there were 13 Terran fleets and 13 Vasudan battle groups.

Determining which planets were Vasudan and which were Terran was a little tougher, but from all the specific references I found concerning which planets belonged to whom, I couldn't escape from the conclusion that only Alpha Centauri, Altair, Vasuda Prime, Aldebaran, and Deneb were Vasudan planets. ALL the other planets in the vicinity of Vasuda Prime had specific references that they were Terran planets, NOT Vasudan. In order to square this with my conclusion that there were 13 Terran fleets and 13 Vasudan battle groups, I came to the conclusion that, in order to help cement the mutual trust and cooperation that arose from fighting the Shivans, the Vasudans would base many of their battle groups in Terran systems and protect them for the Terrans, who were already stretched thin guarding the rest of their systems. BETAC and the formulation of the GTVA no doubt helped cement this gesture of trust and friendship.

1st Fleet: Based at Terra (Cut off from GTA/GTVA when SD Lucifer exploded)
2nd Fleet: Based at Delta Serpentis (the Terran capital since contact with Earth was lost)
3rd Fleet (CONFIRMED): Based at Capella
4th Fleet (CONFIRMED): Based at Vega
5th Fleet: Based at Beta Aquilae
6th Fleet (CONFIRMED): Based at Epsilon Pegasi
7th Fleet: Based at Polaris
8th Fleet: Based at Regulus
9th Fleet: Based at Sirius
10th Fleet: Based at Laramis
11th Fleet: Based at Luyten 726-BA
12th Fleet (CONFIRMED): Based at Ross 128 (a bad Terran assignment)
13th Fleet: Based at Wolf 359 (the REALLY badassignment for Terrans)

The 4th Fleet was based at Vega during the Great War and was still based at Vega during FS2 (I found specific in-game references to both), so I'm guessing the Terrans never re-organized the fleet deployments. The Terrans in the GTVA military are no doubt hoping that the 1st Fleet still exists and will rejoin the GTVA once contact is restored. This is why Earth still has the 1st Fleet based there; it's also a morale issue. Acknowledging the loss of the 1st Fleet (the cream of the crop of the Terran military) would be a huge blow to morale, so it's fleet designation was never changed. (This is ALL guesswork here, but I think it's a good guess.)