Can someone help me figure out why not all of my transactions are pulling in from my linked bank account?

Welcome to the Community space, @transactions-plu.

I can share with you some insights about linking your bank account to QuickBooks Online (QBO).

When you connect your bank account to QuickBooks, the system lets you download the last 90 days of transactions. It also varies depending on your bank.

If you wish to download more than 90 days of transactions, you can upload them manually to your account. Let me guide you through the steps.

1. Log in to your Bank website and follow the instructions to download the file as QBO, .CSV, or .QFX (maximum file size 350KB).
2. Ensure to download only those transactions that haven’t been downloaded to your account to avoid duplicates.
3. Once done, log in to your QBO account and go to the Banking or Transactions menu. 
4. Click the Banking tab and click the blue tile of your preferred bank.
5. Select the Link account drop-down menu and then click Upload from file.
6. Click Browse and then select the file you downloaded from your bank. Then select Next.
7. In the QuickBooks account drop-down, select the account you want to upload the transactions into. Then select Next.
8. Follow the onscreen steps to match the columns on the file with the correct fields in QuickBooks, then click Next.
9. Then simply click Let's go when you're ready. 

You can also check this article for more details: Manually upload transactions into QuickBooks Online. 

In case you’ve downloaded a duplicate transaction, you can just exclude them. You can see this article for reference: Exclude a bank transaction you downloaded into QuickBooks Online. 

Once everything looks good, categorize your transaction to put them in the correct accounts. To be guided, you can utilize this link: Categorize and match online bank transactions in QuickBooks Online.

You're always welcome to tag me in your reply if you need help managing your transactions. I'm just a post away from you. Keep safe!