My advice, as an internet stranger so it's probably not worth a whole lot, but take it for what it is...
You need to focus your energy right now on paying those balances down. That utilization is your biggest obstacle right now. I wouldn't worry about applying for anything (cards, mortgage, whatever) until you take care of that.
You also don't want any new credit when you apply for a mortgage. If you're serious about buying a home next year, then you need to stay in the garden until then. Focus on paying down your balances and keep making your card and loan payments on time. Watch your scores go up as you do. Once you get that utilization down to near 0% you may want to start looking into that mortgage. Don't apply for any new credit until you get it.
Get an INDEPENDENT mortgage broker to pull your credit and shop around for you. He'll tell you if there's anything you need to do to tweak your score. Do whatever he says.
Once you get the house out of the way, then you can work on optimizing your card portfolio and getting rewards for good budgeting and all that.
Travel comes after you've "made it."
You know, I replied to your "why so many" post and forgot to welcome you aboard. So, welcome! I'll tackle a few things for you.
First, while Credit Karma is great for tracking trends and changes in your credit, the scores it gives you are Vantage 3.0 which are not actual FICO scores. For some people they are in the ballpark of their FICO 08 model scores (the ones used by most lenders), for others (usually with limited or spotty credit) they can be significantly higher, and for people with thick, clean credit files they can be as much as 100-110 points lower than actual FICO 08 scores! I'm in that last group - I can qualify for pretty much anything I want, but Credit Karma thinks I may be better off with a secured credit card to establish credit or by getting a high interest, high annual fee card from a predatory lender like Credit One. It is very important to know where your scores actually stand. You can get a huge number of scores from this very site (although it is admittedly pricey). Many people suggest using Credit Check Total which offers a $1 trial and gives you all three FICO 08 scores (I actually have a running subscription with them - if you call to cancel, their automated system will actually offer you 50% off so it's $15 a month - not bad for monthly FICO 08 scores from Equifax and TransUnion, daily Experian scores and credit monitoring alerts for all 3). There are also some free options available. creditscorecard.com is run by Discover and gives you a free Experian FICO 08 score monthly. If you have an iPhone, there is an app called Lenny that gives you a free monthly Equifax FICO 08 score (it may take as long as a month before your first score appears). Many lenders also give regular credit scores. I am not sure if or which one USAA does, and CapOne is a Vantage 3.0 score like Credit Karma.
As the USAA is the joint account, until you get the CapOne cards paid down I would not add him as an authorized user yet as his utilization is just under 49% (still high but not as high as yours). Can you tell us the opening dates (month/year) of the cards? Any annual fees on the Capital One cards? How soon do you think you will be able to pay down the CapOne cards to under 29% (I know you stated January for all 3)? If it were me, I would pay those down first then add him as an authorized user so that he gets the account ages and payment history on his reports - then once you have the newest one paid off, plan to combine the limit into the oldest card (and if the Platinum is the oldest, do a product change to either Quicksilver or Venture One first) at a later date, but make sure that before you do that you have acquired at least 1 additional revolving credit card, which I would not apply for until your overall utilization in under 29% and I would not do within a year of getting a mortgage. Also, have you requested credit line increases on both Capital One cards? There is no harm in asking as it would be a soft pull, and if they do grant them that would greatly help your utilization right now.
Can I assume that if you are able to be USAA members that you also qualify for Navy Federal Credit Union? If so, I would make joining a part of my plans at least 12 months before buying the house. With your auto loan, I would probably make that a priority to do now even with less than perfect credit (I know you have nothing bad, just thin files with high util) as it'll save you a ton of money on not just the loan, but also on interest if you can pay your cards down faster. Navy should be able to drastically lower your auto loan (and Pentagon Federal Credit Union would be even lower, but not sure if you want to open a ton of new accounts now).
Other than that, I wouldn't get too crazy with opening new accounts if a mortgage is in your near future. Just my $0.02
Also since you mention USAA, are you and/or your husband veterans by chance? If so, a VA mortgage is going to be the way to go and you both likely already qualify for the lowest rate so I would change a few things in my advice.
