Help/advice with capitalising advantage

pretty much as the title says.

I've been playing chess for years and whereas I've sat around the 1100-1200 rapid mark for years, I'd obviously like to improve.

I often take breaks from chess as I get a little frustrated with myself for what I'd imagine is a common problem and that's converting advantages.

pretty much every game where I have an advantage, I manage to lose. sometimes on time, but often just because I missed a single good move, or blundered in some way.

now, I'm not asking for a "How can I stop blundering" advice, or "which opening is best for me", because I feel I'm genuinely ok at chess. not great, but ok.

I'm wanting to ask, does anyone have any advice they've used that they feel helped them in learning to capitalise on an advantage. Too many times I lose, even with a +/-5 advantage, just because I fail to convert.

Any help/advice welcome. Thanks in advance!