ha! Dave Noisy - too funny! Of course you'd think she should drop the swimming and running..........
Saucypunk - I just completed my first ever all by myself triathlon in April. It was cool and I'll definitely be continuing them when the season starts again here in Oct!
As far as training - there are some really good websites regarding training for your first triathlon (can't remember them off the top of my head) - just google them. There will be programs that take you from nothing to your first tri.
If you are feeling tired then yes you are probably training too much or not getting enough rest/sleep or not eating enough for the amount of exercise you are doing. I found that I had a slump in the last part of my training (closer to the event) and had to really assess my food intake (was it balanced, included enough protein, carbs etc) and rest periods.
You can do it - I would say get yourself a good bike as soon as you can. I did my race with a mountain bike with road tyres and it was REALLY hard. Have just purchased a road bike and WOW what a difference the proper equipment can make.
Write a plan for yourself and spread your training out thru the week. It's very important to have rest days - COMPLETE rest days where you don't do any tri training. This helps the body recoup and heal. Take it easy and be careful cos you don't want any injuries. Have fun!
Let us know if you have more questions!