pfsense 2.4.4

Hi guys! Im pretty new to virtualization/networking and im experimenting with PfSense in Proxmox. Is it possible to use PfSense in Proxmox with only 1 NIC? I have been trying to set this up for a few days and im getting more and more confused. My plan to get this working might be 100% wrong...

I am having an issue with pfSense Proxmox and VLAN's. My setup has pfSense virtualized with other VM's on the same host and 4 VLAN's. I have a Cisco 3850 switch that is my core. Originally I had all of my intervlan routing occuring inside the Cisco switch and anything that need to get to the WAN...