Its your first race so the most important thing is to stay calm and controlled, don’t worry about pace, speed, etc, just learn to relax and go easy.
The bad news is that where you are now with fitness and technique is pretty much where you will be on race day which is why most people look to taper their training 1-2 weeks prior to the race.
The good news is you look like even through the rather disorganised and unstructured training, you seem to have at least progressed from a few months ago. The best advice for you is to use the time remaining to take stock and consolidate your position especially with the swim.
You will not drown in a wetsuit so get used to being in OW and floating in it and learning to relax and regulate your heart rate and breathing, you will need this if you have a bit of a freak out on race day and panic will fatigue you faster than anything else. Once you have the OW situation in hand, take the swim in segments, there will usually be buoys at the turn points, make sure you memorise the course and sight the buoys, know which positions they lie as once in the water, a pretty important skill which most starters don’t consider is sighting which can be difficult in choppy/brackish conditions and can be disorientating once you start putting your face in the water (No lane lines). Learn to either sight properly as part of your swim stroke or just stop every 10-20 strokes briefly and check if this is easier to make sure you are going the right way. The other method is just to follow the feet in front of you assuming they are going the right way as well.
Depending on the distance, make the first segment the first turn buoy and so on, focus on getting through each segment and don’t worry about the total distance, you can either stop briefly at each point to catch your breath or if you’re feeling good just keep going but don’t be afraid to stop or switch to your backup stroke to get things under control as needed. You’re going to be a back marker so you’ll probably have a lifeguard in a kayak or board nearby so it will be additional assurance that you’ll be fine if you end up getting into trouble to settle any panic. Once past the last turn point you’re in the home stretch to getting out of the water so slow and steady until your feet hit the bottom and you’re done and dusted in the swim. If its 750 metres, then prepare to be in the water 20+ minutes up to maybe 30.
Once the race starts let the faster swimmers go and don’t get caught in the washing machine where you will get people going over the top of you or getting slapped and kicked in the melee, nothing like aquatic fisticuffs to get the panic meter into overdrive as a newbie. A suggestion is to position yourself to an edge of the starting area and back if its a water start and at the back if its a run in start, it can be pretty brutal depending on how many you are sharing the same space with
You’ll be quite fatigued out of the water (a fatigue level or type you’ve probably not experienced to date) so take the first 5-10 minutes on the bike to settle into a rhythm and get your bike mojo settled, don’t push too hard initially as this could negatively impact on your run, once you get settled, go at a pace you feel is good for you.
Only other training focus is what others have posted that you should make brick sessions integral to your training, bike/run especially to ensure your legs are better adapted to running off the bike, at this stage do bike/run bricks at least 2-3 times a week.
Most importantly again, relax, relax, relax, take the swim at an easy pace, enjoy and get the most out of your day. Good Luck!!!