[mothered]

I have the correct password, but when I try to sign in all it says is “suspicious login attempt”

Are you logging In from the same device and IP address that was used when the account was created?

Yes

Then It shouldn't deem It as a suspicious login attempt. There's something that's triggering the message with your current environment, compared to that of when the account was created.

Although It's useless at times, have you contacted Instagram via email?
support@instagram.com