If you have reduced your Vagifem dosage to two a week then it will do nothing for your atrophy. A lot of women on here have experienced what you are going through and if it turns out to be GSM (Vaginal Atrophy) that is causing the UTI's then the following quote from the Position statement for management of GSM should be helpful.
"If symptoms do not improve with vaginal oestrogen, consider increasing the dose, changing preparation (and consider DHEA) or using an additional treatment such as systemic HRT or two local treatments.
The frequency of using these preparations can be increased in women who have persistent symptoms as the doses of these preparations are very low.
Vaginal oestrogens can often improve urinary symptoms, including urinary infections.
Some women use vaginal oestrogen preparations more frequently than the recommended dose to improve symptoms sufficiently, for example Vagifem alternate days instead of twice a week. It is safe to use the treatment in this way as the dose is very low.
Women should be reassured that it is safe for topical oestrogen to continue in the long term (medication should be on a repeat prescription). Women should continue to be reassured about the long- term safety of vaginal oestrogen preparations."