1. If you love Astronomy, you have to do a lot of Mathematics & no other way.
Mathematics needs a kind of mental discipline & time routine. One needs to get into the grove. If A, B or C can do why can't you? Take it as a challenge. Another thing is, if you are tutored it is like swimming by reading a book without your getting into the water. You have to do it yoursel; there is no other way to learn. Do it again & again as a practice.
2. Arithmentic is also Mathematics. But Mathematics is something beyond it. Arithmetical ideas come very handy in Mathematics. Arithmetics at the higher level is a great help in Astronomy where one needs to deal with numbers of extreme order both very big & very tiny. Mathematical ideas start with Algebra, where it is manipulation around the equation that it is all about. This is the stumbling block most people feel that they can hop over everytime instead of getting it out of the way, the initial hurdle that one must get over quickly. Familiary would come fast then. Next, Trigonometry - if you don't know it there is no point in trying to know anything in Astronomy. It is vital. For the love of Astronomy you need to mug up (commit to memory) & fast. These seemingly hard things of which one gets no insight, would reveal themselves later, enriching the experience for anyone, while the others are left far far behind.
The American system of pedagogy is to understand first before learning. Rote learning, memorising is shunned. If the student is given this choice he will have to wait for half a century before he can understand any. But if he is intent upon learning (mastering the fundamentals) he shouldn't be given a choice & he has to take the route of rote learning. The age too (teens) is ideal for it, instead of lamenting later for the things not done at the appropriate age. One can't postpone this activity.
3. After all, Mathmatics is a "language" that one could express ideas in highly compact ways. Mathematics never fails & is ever consistent. So, even after forgetting why you memorised a topic, it would come to memery unfailingly as a tool useful anytime.
4. Once the jinx is broken & you are into Mathematics, you have entry into anything you want by finding your way about, instead of being shunned & kept out for all the time. Remember you can't learn Mathematics after 30s (never). So don't postpone.
5. In school I was a fiasco in Matheamtics. Used to watch others do it & envy. Later I learnt the hard way untutored. And that helped. What I learnt is my own, not given by anyone. It gives me confidence & authority to whatever I say. Professionally too I needed Mathematics that kept me fresh & on my toes. More than that it aided my thinking, made me faster, smarter (I compared with my own self in the past & how it would have been) & cleared my head. From this experience I learnt a few strategies. I don't learn Mathematics as a seperate activity. I read something say, in Astronomy, where I come across 'Spherical Trigonometry' of which I knew nothing. Then I paused on Astronomy & got into Spherical Trigonometry. Because there is a context to it, thinking like an Astronomer I laboured on & mastered it. Now I can solve any problem in Spherical Trigonometry (in Mathematics there are no short-cuts at all). But then it wouldn't have been possible without my funda in Trigonometry (reeling off formulae even in sleep). The same way I mastered the 'magnitude' scale in Astronomy which is really, really convoluted - but not to me now. Break off from Academic approach!!
6. In 21 century (we are still at the beginning) there will be two kinds of people - Mathematically able & Mathematically unable. While the first first kind do things, the second kind attempt, stumble, give up and watch the first one do it.