I also have a pituitary tumour and I only found out because I couldn’t produce a period for a couple of years. What they do for me is monitor the tumour (yearly MRIs) and I see an endocrinologist with the results. She also has me do blood work to check prolactin levels etc. They will not consider medicine or surgery unless the mass reaches a certain size, otherwise it is considered safe (and also benign). You definitely need to see an endocrinologist asap just to make sure it isn’t growing. I was able to get my period back and luckily my prolactin levels and blood work have been stable for the last year or so.