Fear of it happening again....support needed

Hi ladies I am 40 years old,my hubby had a vasectomy 23 years ago,we went through <a href="https://glowing.com/glow-fertility-program">ivf</a> had 2 cycles which both failed,we then had to turn to donor sperm,I was inseminated on the 17-7-17 had the dreaded 2WW we then finally found out we were excepting which was the best thing,on the 3rd I had my HCG level done it was 27 then on the 8-8 I had some spotting so I went straight to my dr and they did another HCG it was 17, on the 9-8 again HCG was 7 I also started bleeding really heavy unfortunately I had miscarried,in the mean time not once was my progesterone level checked,so I requested it to be Checked it came Back as level 2,I had a recent ultrasound and everything came Back all clear I had a complete miscarriage,I am wanting TTC again late October early November but I am really scared that it will happen again,I am due to see a gyno on the 29-8 has anyone else been through the same situation and been able to carry baby to full term and delivered a healthy baby,I really wanna think positive and trying to but it's always in the back of my mind what if it happens again,some advice or support would really be greatly appreciated....and advice on what I can take that really works to help with egg quality,I've been taking COQ10 150mg and what's the best supplements that I can also take to help prepare my body for conception.....I was taking fertile aid and fertile cm........please advice or support would really go along way I really need to have that positive thinking back