High reps and low resistance.
Be sure that when you weight train that you use both types of contractions. There are concentric contractions when you lift the weight and that works the belly of the muscle when the muscle shortens and there are eccentric contractions when you lower the weight when the muscle lengthens and that works where the muscle originates and inserts on and across the joint. For example if you do a biceps curl, when you bring the weight up you can see the biceps muscle shorten but if you slowly lower the weight, overcoming gravity, you are strengthening the muscle at the two sides of the belly. This is what builds strength and not bulk.
I'm sure someone where you work out can give you some guidance but remember that after 72 hours you start losing the gains you have previously attained.
An alternative training regiment might be to swim which works the upper body plus it will give you an excuse to shave your body......
Sorry I Ever Lifted Weights
As a young man I had every desire to present myself as a 'man'. I was into sports and I was into weight-training. I did this because everyone expected me to be a 'man'. Little did anyone know THE OTHER SIDE of ME. I secretly wanted to be very feminine. I did everything I could to keep this side of me from everyone. Had I known then all that I know now I would have transitioned. At one point I was about 20 pounds away from benching 400#. Then the army called and most of my lifting was confined to much lighter weights and attempts after that. I believe as a result of all my weight training and then essentially not doing it anymore was the fact that my breasts became flabbier and larger. I have since torn both rotator cuffs and if I practice I can do 60# on the bench. I can't even do a push up anymore. I still exercise regularly (mostly bicycle) but anything I do is geared toward a more feminine body...