I had these problems with Utrogestan - it's not as powerful as the synthetic progesterones, so for some women it doesn't protect the womb lining so well and erratic and problematic bleeding results. If you try using it vaginally, as many women on this forum do, then this may work better. The problem with using it vaginally is that will irritate the bladder more - I found I couldn't' use it this way as it made my whole ‘lady bits' sore!!!
The UTI symptoms are probably urogenital atrophy and that needs local oestrogen e.g. Vagifem, so ask the GP for this. Also in-between using Vagifem, you probably need some vaginal moisturiser e.g. SYLK or the YES products which you can buy online. Do drink lots of water and avoid fruit juices, caffein and alcohol - in other words anything that makes you urine too acidic. Try having half a teaspoon of bicarb of soda in a glass of water, morning and night, for 2-3 days as this will settle the UTI symptoms and sooth the bladder. You could also try taking an antihistermine at night e.g. Nytol as this can have a calming effect on the bladder.
I suspect your lining built up over the time you didn't bleed, so now it is spontaneously shedding and this can happen with high oestrogen usage and too little progesterone. Many women seem to do fine with Studd's regime but others do not. It's the withdrawal of progesterone that triggers the bleed but, my private gynaecologist explained that, if there hasn't been enough progesterone for the right amount of days to trigger a full bleed, this is why erratic bleeding will occur. HE told me that 12-14 days of any progesterone was the ideal and 10 days the minimum, depending on the amount of oestrogen you were using.
How do you feel on the Utrogestan?
The standard dose of Utrogestan is 200mg for 12 days each month and this might sort your cycle out better. With a high dose of oestrogen, you probably need a higher dose of progesterone.
You do need to get back in touch with Studd to get some help. DG x