Re-Introduction and still TTC IVF baby #2 (Child/pregnancy mentioned)

Good Morning ladies. I haven't posted on this board in a very long time. I had my first child in 2016 through IVF after 6 years of meds and trying TI with no success except for 6 miscarriages, and I was active back then. 2 years later (2018) we started the FET process for baby 2 which resulted in 1, maybe 2 losses and 2 failed and a second IVF retrieval and ERA thrown in for fun...sarcasm there. I say maybe 2 losses b/c we are now at the tail end of our 4th FET (BFP but slow rising 3rd beta...and we all know what that means). 
I'm posting b/c I just at a loss...I've been through so many losses and I really don't know if I have the energy to continue with FET's, we have 4 embryos left. I feel obligated to try since we went through another retrieval recently. We haven't done PGS...money issues, b/c we are throwing everything we have into this and there just isn't much left to throw at these procedures/tests outside of the necessary FET cycles. Has anyone been through multiple failed FET's and can still see some light? I am very grateful for my son and will be more than happy with just him, however, I'm a twin and have other siblings and I loved that and my sister is my best friend and so I hope one day I can give him a sibling to hopefully experience that kind of relationship. If we continue, I just don't know if I should take a break or just jump right back in after this cycle ends...

I guess I'm just venting and looking for advice to keep moving forward b/c it's just so hard. 
Thanks for reading if you've gotten this far!