Reoccurring UTI in my 2 year old HELP!

What a journey this one has been. My poor baby girl has been suffering from urine tract infections for quite some time now. I think I need more support than any thing. Obviously any feedback will be well accepted. My girl has had 6 UTIS since august of 2020 (we are now in February 2021 do the math those are back to back every month) each time she has been on antibiotics. in January they put her on the strongest ones for a whole month. This last one she has though she had to have her antibiotics changed due to her being unresponsive to the antibiotics due to building immunity to them. So this past couple of Weeks I have been on a venture to figure out how else I can help my baby. I went and got her some of the good probiotics ( garden of life it is a chewable pill) and I also invested in some powdered D-mannose. I spoke to a nutritionist and herbalist and this is our plan of attack being the drs are not coming up with a solution. We love her dr but every test for reflux and her kidneys come back perfectly fine. She can’t keep taking antibiotics like they have been giving her either. So any other moms struggling with this or have any experience with D-mannose? Or have a better probiotic suggestion? We have a follow up in March with her urologist going to ask about checking into any auto ammune problems. I’m just feeling really hopeless and see no end in sight at this point.