Of course you can attempt DIY. I have no idea how well you will do. Get the concerns notice wrong, or your pleadings wrong, and you likely hamstring your own case and if you lose and she has high priced lawyers you'll be paying a significant portion of her costs.
FYI, you have 1 year from the date of 'publication' to initiate a defamation case.
Even the big boys get it wrong. Hockey went for broke and it cost him, even though he 'won' against Fairfax. The Tele the tried to amend their defense against Rush and were refused.
Damages in your situation are not going to be a windfall, likely more than $1,000, less than $100K if you are not a very high income earner and not prominent in the community. Though having said that I have no idea of what your reputation is worth.