given the issues with your girlfriend, i believe you are still going to have to sort some stuff out before you seriously consider children - if for no other reason than to be in a healthy and happy head space yourself. assisted conception is hard work, pregnancy (which i'm only part way into) is no walk in the park! if you're ready to go it solo, so be it, but you have to be in a good head space to survive it

i don't know that, in your circumstances, i'd label myself as having fertility issues. you might have been having unprotected sex with your shag buddy for a couple of years, but if you're not constantly trying, having sex at the right time etc, it might just be that you're missing your fertile window. unfortunately casual sex doesn't always lead to pregnancy.... i'd be querying why you think you have fertility issues - if it's just because of the unprotected sex thing, i think you'd need to re-assess that thought - it's not something that you can expect to happen like that. if there is another reason, then for sure, go and investigate

IF you're going to go the assisted conception route, will your shag buddy provide donor sample for you? getting access to anonymous donor is very difficult...