fertility meds first time

Hi ladies. Just after some advice. This is my first cycle on meds. I was on gonal f for 5 days and had my day 7 bloods and ultra sound yesterday and was told to trigger as my follicle is 18.5 and another one (not sure of the size) I'm worried that cd 7 is too soon tho for a healthy egg and lining? She said my lining looks thick but didn't give me a number so I dont really know if that just means maybe I didn't shed it all during my period because how could it be "thick" by cd 7?! Do the meds help with that process too?? Also, should I be asking for bloods to be done in 7 days to check progesterone as I've muscarried in the past? Any insight would be great as I'm
Just concerned it's all happening so early in my cycle and the specialist is very vague!  Thanks in advance.