Am I overthinking?

So I’ve been with my boyfriend for nearly 2 years now, when we first got together we had sex pretty much every day sometimes a few times a day, fast forward to lockdown and admittedly I’ve put on a few lbs (I was a size 10 now probably at 12/14) I’ve always had body confidence issues etc. We are trying for our first and recently I don’t feel like he wants to have sex with me, it’s gone down to probably once or twice every few weeks. I’m now on a strict diet and trying to lose weight but I just feel really unattractive and heavy. What makes it worse is that all his exes have all been very slim and I think that’s making me even more paranoid. I’ve told him that I need more sex from him (I have a very high sex drive) and he said we will do it more often but then never follows up with it to the point I feel like I’m mithering him for sex!!

Do you think I am overthinking things or does he just not find me attractive anymore?! I’m at my wits end!