@Anonymous, you can get your three FICO 8 scores along with the corresponding reports by signing up for a $1 trial at CreditCheck Total, then canceling before the trial period is up. There are people here who do that frequently. From what I understand, you can use the same login for subsequent trials.
Don't do anything until you take care of the Capital One cards. One of them is maxed (over 88.9% of its limit). That clobbers your scores, and other lenders are likely to take notice if you apply for new cards or CLIs (credit limit increases). Also, keep in mind that for CLI purposes, Capital One likes pay-in-full behavior.
Search the forum for AZEO. That means reporting a small balance on one card with the others reporting zero. Not knowing your FICO scores, we don't know how necessary it is for you to do this. But it's definitely something to do if your scores are low. Short of AZEO, 28.9% utilization is considered responsible borrowing. And staying under that number generally puts one in the second best scoring tier for overall utilization.
Once your reports and scores are shaped up, definitely apply for CLIs. You can ask for three times your current limit on your AMEX card once it's 61 day old. If you're denied, you'll need to wait 91 days to ask again. If you're approved, you can ask again in 181 days.
Also ask for CLIs on your Discover and Capital One cards. If you're denied, there's no time limit before you can ask again.
Your assumption that you should be gardening is probably correct. If you could list the dates that you opened your accounts, we could tell you for sure, and we could suggest a time when you can consider applying for another card or two. It'd also be helpful to have this information on your Comenity cards.
You'll probably want to close Fingerhut eventually. I don't see any harm in having the card around for now, but there are better places to shop. 
