You've been trying almost two years, at the two year stage I'm not sure how they can refuse a Fertility referral You might end up having to have further testing done, you might not be eligible for IVF yet (you might not even need it obviously) but they shouldn't delay you receiving appropriate fertility testing from a fertility clinic.
If they did refuse, I would write a polite letter of enquiry to your Practice Manager (or ask the GP directly if you're less dramatic than me) asking them to explain how, when and on what grounds you'd be entitled to such a referral.
33 is young but not when you approach the need for further TTC help. Can you arrange a phone appointment with your GP? Ask them if they'll look at your husband's results and do the referral on the basis that he's got a very low concentration of sperm, and of those there, they are mostly non progressive motility? No amount of being young or continuing to try for years is likely to change that.
I've got PCOS and don't always ovulate. I went for a scan so they could say 'yep, you still have pcos', 21 day blood test could neither confirm nor sent ovulation, plus two years TTC, but that wasn't "enough" for a Fertility referral, but the sperm analysis being shocking was enough on it's own (I'm too fat for it though, trying to shed the pounds for a Christmas referral 🤞).
I think a hysteroscopy is what they do to look for those abnormalities isn't it? People I know with endometriosis or heavy periods have had them and had polyps or endo removed. It's probably worth having (in my opinion, someone who has never had it done).
Utterly frustrating isn't it? You really need to fight your own corner and be your own advocate. Often goes against our need to people please, but really necessary at this stage.
Has your DH done all the things that can help?
Conception vitamins for men (my husband has been taking Wellman conception - will find out next month if they've made any difference), people rave about Impryl (£60 a month!). Not smoking/reducing alcohol/no hot baths/not cycling/loose boxers only/drinking lots of water/being a healthy weight... That kind of thing? If so, make this clear to your GP too!