Please advise on this

So I desperately need some input here...My husband and I are TTC. He is my 2nd husband and I have a child from my 1st marriage. This man is the most incredible man I have ever known and he loves my son better than his own biological father does. We have a great life and I would love to have a baby together, but I’m starting to wonder if he has low testosterone. It’s either that or he just isn’t sexually interested in me. He can go for 2 weeks without and be just fine but it makes me feel so undesirable. We haven’t been married quite 2 years and life is busy, but I’m just trying to figure out if there is a medical reason behind his lack of desire for me. He goes for a semen analysis in a few weeks but I just wanted to see if any of you ladies have dealt with low testosterone and if so, what did you notice with it....Thank you so much....