thanks for writing here.
Since you are getting pimples at a later age of life there is a chance of some hormonal disturbances or polycystic ovary.
You need to undergo blood investigations for hormone profiles and ultrasound
to rule out cyst.
If all these turns out to be normal then you have to take oral retinoids
.You can discuss these things with your doctor.
Continue with tretinoin
cream.Do not try to squeeze the lesions.Use a good oil control face wash.Avoid any occlusive moisturizer on face.
I hope this will solve your problem.Take care.