I have a laptop which is a Dell E6440 and was just wondering if it vulnerable to these DMA attacks through Thunderbolt and Firewire methods.

Reason asking, is because I have BitLocker full disk encryption turned ON with TPM-Only protection (meaning no PIN).
Would this be fine or how can I tell if my laptop is vulnerable to DMA or Memory attacks?

Overall, is it OK to use BitLocker with TPM-only protection or do I need a PIN as well?