The issue I have with your weapons suite is that of range. As a forinstance, my own heavy ships tend to be armed with two sets of primary weapons, a perfect 50/50 split. These are missile/beam salvo turrets with a range of 4.8 sectors. Each turret with these weapons fires a few extremely powerful missiles 1-2 million damage each 'plus' over twenty single module missile/beam decoys per turret to help the big ones penetrate point defense. I have a great many of these turrets. The other primary weapon turrets are cannon/beam with a range of 3 sectors. These too are meta-weapons whose combinations are designed to accentuate their effect. All the turrets feature some ion to assist in shield dropping, punch to help penetrate armor and explosive to deal better interior damage.
In addition to those primary weapons, roughly 25% of my total weapons tonnage is devoted to defensive armament; a great many anti-missile point defense turrets and a fair number larger of cannon/cannon anti-drone turrets. The anti-drone turrets fire ten times a second for 2000 damage per shot, which is enough to crack heavy armor despite any armor hit point pool. Each such anti-drone also has a little over 200 modules of a cannon/cannon/stop weapon designed to stop drones in their tracks. It would take a very large drone to not be held locked in place while one (or more) of these turrets pours fire onto them.
Back to the point I would make about the primary missile/beam and cannon/beam weapons. Their range is between 4.8 and 3 sectors. I also design my ships to have decent acceleration, so as to allow me to control the range. I even throw in the tiniest bit of overdrive. My plan is to close to missile range and stop. If my opponent attempts to close the range, I fly backwards to maintain the range. If when approaching engagement range, I see my opponent also attempting to close, I will stop well before missile range and begin retrograde flight well before they reach missile range so I already have movement to compensate for their closure.
In all likelihood, none of your weapons would ever be able to hit me. You are simply too big and too slow to be able to dictate the range of the engagement. The only way you could do so would be to jump to try to catch me inside of your own engagement range. This is not impossible, but it is highly likely that if you did so, only your turrets would be able to engage, as it is unlikely I would be close to your primary weapons crosshairs after such a jump and your turning would simply be too slow. Meanwhile, virtually all of my firepower 'is' in turrets, and now you are in range of my anti-drone turrets too.
I say this not as one upmanship. I am not trying to be 'better' than you. I am pointing out that the primary problem with weapons choices is actually far less about how big to make weapons than it is about the strategy of how to use them. A titan is slow. You have no chance of controlling the range except versus another titan and then 'only' if you have sacrificed some defense (as I have done) in order to be able to control range. Even then, you will only control range versus other titans, as everything smaller will be absolutely able to maintain their preferred range.
If for instance your opponent devotes his tonnage to a drone fleet and arms those drones with nothing but say, missile/beam weapons, their drone AIs will keep them at their extreme missile range and you will NEVER be able to engage them with anything near enough firepower to make a dent in them before they bring you down. As a for instance,
here is a 1000 mass drone frigate such a player could deploy en mass. Each one of these does a million damage (potential) every 45 seconds. In an equal mass matchup with your titan, an opponent could field 680 of these things. Their alpha would have a potential for 680 million damage and then another again 45 seconds later, and again and again and again...
Titans are an interesting design project, but they are NOT the be all and end all of fleets. My own titan design could not stand up to such a drone fleet. (Though it would get in a few licks with it's missile turrets.) It probably couldn't stand up to a tenth that tonnage.