It is unfotunate you haven't found the right specialist to properly help you, you have the right to be well taken care of and get your questions and concerns answered.

Your new cardiologist may be better so you may want to give him/her an opportunity, if not my recommendation is that you travel to the closest major medical center to get properly checked (you mentioned they don't exist near you). Do your research find a surgeon who has done lots of these surgeries. Check their bios, normally those will describe their experience and research interests. Same if you need a new cardiologist, it does make a big difference to find one who truly understands aneurysms and provides you with the right guidance and periodical controls. I attached a screenshot of what appears in my Cardiologist bio and an excerpt from my surgeon's bio as examples.

Now, I am not a Dr but can tell you my opinion from what I have learened and understand. At less than 4.5 cm (let's call it that until you get a more accurate measurement) you are far from the critical size, (but you absolutely should get monitored), normal regular exercise should be fine and actually highly recommended so that you keep yourself in good shape. The main thing to keep under control is your BP, high BP is the main enemy of aneurysms, think of a balloon the more you inflate the thiner and more vulnerable the wall gets. The consensus is to avoid any exercise that would lead you to hold your breath and grunt while exerting, that is why they tell people to limit the amount of weight they lift, not because of the movement or weight but because the more weight, the more you exert and the more likely you will hold your breath to maintain spine stability. It is proven that while you exert holding your breath, your BP rises significantly albeit for short periods of time, those peaks although short a very detrimental because they are also very high. (I have posted two videos that talk about the subject of exercise and aneurysms, you may want to look for them under my handle in this forum, if you don't find them I will be glad to look for them and send them to you)

As far as I understand, at less than 4.5cm the probability of disection or rupture are close to zero and that is why the monitoring is usually annual (I have heard 6 months in some cases but yearly is more common unless the growth is significant)

I hope you find the right professional support and find a way to help you with anxiety (consider a good therapist also)

As far as diagnostic tools, it is my understanding that a gated CT scan (to eliminate inaccuracies due the movement of your heart) with contrast is the gold standard and is going to give you the most accurate reading. Echos and a non-gated CT scan are going to have some level of inaccuracy. In my own case, the difference between a non-gated CT scan and a CT scan was 0.2 cm. So, wait for the June 2025 scan and make sure it is a gated one with contrast, which should be accurate. As others have said, at either of the sizes you mentioned your risk of an incident is very low (below 1% over the next 5 years) until it gets above 5.0. Most doctors recommend light to moderate exercise even with an aneurysm as long as you avoid lifting heavy weights.