you need a coulombmeter on the battery. Everything going in/out of the battery has to go through the coulombmeter. The lifepo4 battery you are using the resting voltage remains about the same 13.1 volts from 10 to 90 percent, so its impossible to gauge the battery level using voltage. The coulombmeter counts the amps going in and out of the battery. For instance if you use 20 amps today, you know tommorow you have to put 20 amps back in. I use the tk15 coulombmeter, on amazon (50a model) they are around 60 dollars, on ebay you can find them for less then 30 but are ship from china, if its speedpak shipping you might get in less then 2 weeks.
To get maximun amps from your panel you need a "true" mppt controller, if you can put a picture on your post we can get an idea if it is really an mppt or a pwm controller. An mppt controller will get about 12 amps of charge power from your panel, a pwm controller will only get 6 amps of charge power. For right now you might get away with a pwm controller but when winter comes, you need to extract every ounce of amps from your solar panel. A true mppt will be large and heavy with metal heatsinks, a pwm will be smaller and be mostly plastic. The victron 75/15 mppt is what alot of people use, its in the 100 dollar range. On youtube you can see reviews of different mppt controllers.
If you had the money the makeskyblue 60a mppt (cost 130) is what I recommend and I used and tested it with both a 240 panel and also a 365 panel. I recommend the 50a or 60a models because they are the only ones that advertised having a feature to deal with bms activation (it won't produce voltage surges). I learrned the hard way about voltage surges from solar controllers and lithium batteries.
One other place I use a meter is between the controller and battery, I use a bright LED, the reason is so you can read it in daylight and from a distance. With this meter it tells you what the voltage and amps going into your battery. Extremely useful and very easy to see how your solar system and battery are performing. I been using a 90 volt 30 amp combometer (20 dollars on ebay) for the past 8 years, I never turned it off. The coulombmeter will tell you the same information but you need to be right next to it to read it. Also the combometer doesnt require a shunt, very easy to install.
I would probably also get a smaller inverter in the 200 watt range to run smaller devices like laptops etc, the 1500 watt inverter consumes too much power when at idle or running small devices. 1500 watts is only to turn on to run your large device and turn off as soon as your done.
