to the forum Papaya Rain!
It is tough to make time for ourselves but so very worth it! 4-5 exercises/body part in which you are doing 4 sets of 8-10 reps is a lot. If you are just beginning your lifting or consider yourself a beginner two sets of 8 to 12 reps two to three days a week will be the range you want to work within. You may be able to cut back on the number of exercises you are doing by ensuring that you are incorporating compound exercises into your routine. These are exercises that hit more than on major muscle group at a time. Compound exercises are also important because our muscles do not work in isolation of each other in the real world. Rather, they work in concert together and thus training them in the same way will only improve their performance in everyday activities as well as prevent unnecessary imbalances and thus injury.
Within your message you indicated a goal of seeing muscle definition. This will be acquired as you continue to lose bodyfat through clean eating.
If you would like to gain strength you can select a weight that will allow you to reach fatigue or failure within 4 to 6 reps. If you would like to increase muscle endurance choose a weight that you can lift 12 to 15 reps before you reach fatigue. Generally though 8 to 10 or 12 reps is a good mix of the two goals and generally where I tend to stay as well. I know that when I am consistently hitting at 12 reps it is time to lift a little heavier weight the next day in the rotation.
You may already be aware of The New Rules of Lifting for Women by Lou Schulerc, Cassandra Forsythe, and Alwyn Cosgrove. If not, check it out from your local library if it is available. There is a lot of valuable information written to assist someone who is in the early stages of lifting.
You are so right to keep exercise as a part of your lifestyle even with all the other demands. Congratulations and keep up the good work.