You are overthinking this (especially since you are already so close in number). Asking for 2k more is probably less than 2% of your total cost to that company.
I would suggest something like:
- "First, thank you so much for the offer. I am excited for the opportunity! I'm very seriously considering the offer, but was hoping to see something closer to $75k and a small signing bonus, as my experience with our technology and products will let me immediately begin contributing. What flexibility with this number do you have?"
Or if you want $72k instead of $75k you can say that. As a software engineer you probably could ask for $6k more and get it nearly no questions asked. But replace that with whatever you want.
In most cases the worst they can do is say "no." A company which withdraws a counteroffer asked well (not "I absolutely refuse. I need at least $71k instead of $69k" or whatever) probably is not a place you want to work. Just don't make it a "I reject this offer, and have my own demands" and you'll be fine.
FYI, the company accepts salary negotiations, however, I'm not sure if I'm reaching too far in the cookie jar.
Negotiation is a business interaction for your manager. It has a huge impact on you personally as it is your personal income, but for your manager, it hardly matters and is a minor blip on their daily activities.
Think of it this way: your manager isn't paying you out of a personal pocket. Most places have a budget for positions and as long as the person is good they have flexibility on numbers. If another $2k saves them the hassle of interviewing... that's probably ok to them.
If you argue with your manager about this back and forth multiple rounds, that's one thing, but a simple salary negotiation doesn't really matter much.