IVF first beta on the lower side

Hi girls, Just had my first Beta 11dp5dt and they said it's on the lower side it's 90, but my progesterone is good and high at 121. The worst thing is that I'm sick with cold/flu for the past few days and feeling terrible, not sleeping, coughing and I even had a fever and it's freaking me out. This is our #4 fresh cycle. We had one natural misscarige at 8 weeks 2 years ago and one <a href="https://glowing.com/glow-fertility-program">ivf</a> chemical pregnancy where the hcg was only 15. It is really hard to stay positive after everything and I just need a bit of reassurance from you girls.