Definitely more panels. Your 300w set right now might fill a single battery in a day if it never gets used, but not 2 and not enough to fill a battery AND run anything else. For 200Ah of batteries the math looks something like this:
12.8v @ 100Ah = 1280 watt hours (Wh) of power *2 batteries = 2500Wh of power.
2500Wh / 5 average good direct straight sun hours = 500w
So you'd need at least 500w of solar panel in perfect conditions in direct straight on sun at perfect room temperature to fill those batteries in a day. You've got that so
Then there are the loads you want to run during the day and if you have a guess as to how much that draw is, add that up in panels.
All inverters have electronics inside that stay on and need a little power just to exist standing by ready to do anything. That's called "No load draw" or "Standby Draw" and usually it's not much, but the larger the inverter the more power it needs just to sit there and exist. As an example, my Growatt 3Kw unit uses about 60w just sitting there turned on ready to go which doesn't sound like much, but when it's 60w for 24 hours it adds up to about 25% of my 8Kwh battery to do nothing. Stand alone inverters in your size are probably somewhere in the 20w range, or about 500Wh a day just sitting there. When you're using standard 100Ah LFPO batteries, that's almost half a battery a day in standby.
There are inverters that use very little standby power, but IMHO they're not worth it because the cost difference between a 20w draw inverter and a 5w draw inverter is usually around the same price as 2 or 3 more batteries.
The big issue I keep coming back to here is where your batteries are down in the 11v range, that's bone dry dead! Those batteries need to get charged up because while you may have 2500Wh of capacity, there only seems to be about 250Wh actually in the tank. Do you have/can you beg/borrow/steal a regular battery charger from someone and throw that on the batteries? A regular battery charger will get you up into the 90%ish range at least and you can connect it up right along side the solar array (just clamp the terminals to the batteries, it's fine) and let the charger help out the solar.
I think if you got the batteries fully charged you'd see a world of difference in how things run.