Welcome Justina - hope your stay with us is short and sweet!
In regards to your cycle, it is very common for FS's to not allow you to do a FET straight after a stim so that your body can recover from all the hormones and get back to 'normal' (whatever that is when you are doing IVF!). I don't think it's at all suprising then that your body isn't responding as it normally does if you are having a natural FET the following month - my cycles are 28 days and my cycle after my stim was 35 days if this helps
Hope your BT shows your ovulate soon and I am sure your embie will be just fine, as you have quite a few embies in the freezer, you shouldn't worry about not having any embies to transfer.