Period

Hi mums this is not a baby related post It has to do with periods. I have noticed in my last two cycles that my flow is much less than usual. Last cycle i got my period 3 days late and when they arrived they were light in the sense of flow i could see blood when i wiped but not much in mu pad. The next day it was better and then i had a bit more on the third day and they stopped. I did a pregnancy test and it was negative. I did not think much after that. This cycle my flow was much lighter than the last time.. i barely had any flow and my pad was all clean. I could see blood on the toilet and even noticed two clots down toilet.. but now flow at all in the pad. I did have blood in the wipe which was more first two days… in the third day i did have a bit in the wipe again but nothing in the pad. I did a test yesterday it was negative. I am getting so worried what this might be. I ised to have very regular period up until March this year with normal flow lasting up to 4 days sometimes 5. We started to try for a baby in April and this happens right a way and its disappointing. i am 37 and i have a son but want to have another baby. NOTE: I have requested a GP appointment and have one on 18 June. But till then looks like a long time and wanted to see if any of you have experienced this before and what might be the cause. Thanks mama