Don't listen to CK's "advice" and "pre approvals." Those pre approvals are marketing and nothing more. Also, more credit does not mean better credit. You could have $5,000 in total available credit or $50,000. FICO doesn't care. All FICO cares about is how much of your available credit you utilize. Ideally, keep it under 30% individually and 10% total. You seem to already be well below those thresholds, so you're great. You also already have the recommended 3 CC's, so no real need to get more unless maybe you plan on replacing that Total Visa (which I would if I were you, at some point).
That said, applying for cards doesn't necessarily automatically lower your scores. HPs for credit apps don't always lower your scores; if anything the new account hit does, but only if you fall below certain aging thresholds. If you do decide to apply for a new card, definitely don't go off of Credit Karma or any credit monitoring site's "pre approvals." Do your research and apply for something that will benefit you, is plausible, and you actually want.
I'll second what @OmarGB9 said. Last year, I fell for being 'pre-approved' by Credit Karma but was denied but the creditor. Although the CK link was one of those 'applying won't affect your credit' links and they only did a soft pull. So, I don't know if that is a CK thing or just happened to be that creditor. I stopped applying through CK after that.
Now, I just go to individual pre-approval sites from the creditor and see if I can get pre-approved before applying. That greatly reduces the chances of a hard inquiry with a credit denial on top of it. I would search if the cards you want have pre-approval sites and start there.
