OK, It would seem that your smart meter has been configured to show something, but it isn’t clear what. I very much doubt that you can reconfigure the LED to show anything useful - you can’t get nett usage out of it via the LED (because the LED can’t show the direction of energy flow), and it can’t know what the generation is. All you could possibly get from the LED (if your supplier will even let you change it) is either the import or the export or both (but without differentiating between them).
I think it’s either an emonPi, or if you’re up to building it, something very similar - using two c.t’s, one on the grid infeed and the other on the PV infeed. A simple subtraction will give you your usage, the Grid power can be separated (by the sign, you must monitor voltage to determine the direction of power flow) into import and export, and you’ve got all the information you need. The bonus is it’s all under your control.
Would every 5 or 10 s, or even less, be fine enough? That’s what you can have with analogue monitoring. Pulses are fine, but historical. All you know from a pulse is you’ve just used one quantum of energy (1 Wh in your case) - you can’t know whether it went to a LED light over the last n minutes, or an electric kettle for a fraction of a second before.