The war with the Cylons lasted for around a thousand yahrens (hence the name), and during this time, Colonial Fleet Strength flucuated widely. These notes are intended to give some indication of the strength and composition of the Fleet at various stages of the war.
The Colonial fleet is large and able. It consists of many types of ships of all sizes and is able to put large numbers of warships in the field. An example of this is the Fourth Fleet which consists of some six hundred fighting vessels (including two Battlestars) and was sent to battle in 7312. Then in 7328 the Battlestar Pegasus leads another fleet into action. As such, whilst I do not expect too many fleets of this size could be fielded at one time, they could be fielded (and lost) without too much concern from the Colonial High Command. In addition, forces would be around to defend Colonial holdings and the homeworlds while fleets went on the offensive.
By 7300, the amount of Fleets able to be fielded would be reduced to about 2 at any one time, with additional fleet elements around for patrol and defence.
This point in time is around the time that Commander Cain left with his Fifth Fleet in the last Colonial gamble of the war - the doomed Battle of Molecay.
While the battle is mentioned in "The Living Legend", the reasoning behind it may be a fandom thing. Even so, it has fallen in historical use and so deserves mentioning here. The Fifth Fleet was sent as a last gamble to shatter the backbone of the Cylon offensive and buy time for the Colonials to re-group, re-arm and win back the offensive. While we do not know exactly how large the fleet was, we do know that it consisted of almost everything the Colonials had at that point, including all but five Battlestars and a few lighter elements. At this point, I think only six Battlestars remained in service, and five stayed behind to defend the Colonies. However, all other heavy ships (heavy cruisers, Gunstars) and most lighter ships that were surviving went with the fleet. I think the intention was, that as Commander Cain was leading the fleet, it was assumed that it couldn't fail and thus the stripping of ships and defensive resources was deemed acceptable as the fleet would be back long before the Cylons could take advantage of the fact. Not that they would be able to do anything about it at that time anyway.
Unfortunately the plan failed, and the fleet was all but destroyed. The only known surviving vessel was the Battlestar Pegasus, but this would not be known until after the final destruction on of the Colonies.
Thus at the beginning of the year, the Colonials had a few hundred warships in their fleet, which was bearing the brunt of the Cylon invasion, although in a much reduced sphere of influence. 90%+ of this fleet went with the Fifth Fleet.
We know for a fact that at the time of the peace conference the Colonials had 5 Battlestars surviving - the Acropolis, Atlantia, Galactica, Triton, Pacifica. We see them. However, we can also guess that other forces existed, although probably nothing as large as a Battlestar. We can deduce this from the following facts:
1: When the Galactica is recovering the surviving elements of the fleet, a total of 67 Vipers are recovered, some twenty five from the Galactica. It is told earlier that no other Battlestars were able to launch fighters, so these fighters had to come from somewhere. They could have some from planetary defence bases (we know the Cylons have physcially attacked the Colonial Worlds before, so it would make sense that the various planets has ground bases which may have had fighters present). However these fighters could easily have come from ships left behind.
2: We know that piracy exists around in and around the Colonial worlds - Commander Croft who leads the mission against the Cylon asteroid gun "Gun on Ice Planet Zero" was a captured pirate. As such, while it might be a good idea to take the majority of the Colonial Fleet on a "peace mission", it would be stupid to leave the entire Colonial worlds undefended. Also because the war has been going on for some thousand yahrens it would be tactically stupid too as well. These additional vessels may not necessarily be at the homeworlds at that time (I think that Cimtar is pretty close to the homeworlds to respond to any distress calls quickly, and also see above for additional Viper support), but could be out patrolling other areas of Colonial space, or what it left of it at that time.
3: Another slight clue comes in the film, when a Centurion is reporting the rumours of an exodus fleet to the Imperious Leader. He mentions that survivors tell of a warship which got away, and the Imperious Leader asks "What kind of warship?". Now, obviously this can be taken in many ways, but it can also be taken to mean that there were more than just Battlestars present at this time. For starters, if nothing but the Five Battlestars were still around, this question would be largely irrelevant as the Leader would know, through his spy Baltar, that the Colonials would only be sending Battlestars to get ambushed. Secondly, I am ignoring the fact the Leader could be referring to Vipers, after all, while Colonials pilots can be very good at what they do, what possible threat is a mere Viper against a Cylon Empire? So, if we are not talking Vipers or Battlestars, what else is there? Ergo, some other type of warship.
4: Yet another clue comes in from the background chatter on the Galactica bridge during the battle at the Moon of Cimtar. If you listen really closely, you will hear the names of a couple of other ships - like the Triton. Are these ships the Battlestars themselves, or are they, as rumour has it, fleet escorts or other small cruisers.
Thus I think that at the time of the Peace Conferance, the Colonial forces consist of some five Battlestars and assorted smaller vessels (probably mainly light cruisers and maybe a few destroyer sized vessels). No larger vessels or heavy cruisers exist at this point - having been destroyed with the Fifth Fleet.